1. install acu4c

take@MacBook-Air ~/g/gollum> brew install icu4c
Warning: You are using OS X 10.11.
We do not provide support for this pre-release version.
You may encounter build failures or other breakage.
==> Downloading https://ssl.icu-project.org/files/icu4c/55.1/icu4c-55_1-src.tgz
==> Downloading from http://jaist.dl.sourceforge.net/project/icu/ICU4C/55.1/icu4c-55
######################################################################## 100.0%
==> ./configure --prefix=/usr/local/Cellar/icu4c/55.1 --disable-samples --disable-te
==> make
==> make install
==> Caveats
This formula is keg-only, which means it was not symlinked into /usr/local.

OS X provides libicucore.dylib (but nothing else).

Generally there are no consequences of this for you. If you build your
own software and it requires this formula, you'll need to add to your
build variables:

    LDFLAGS:  -L/usr/local/opt/icu4c/lib
    CPPFLAGS: -I/usr/local/opt/icu4c/include

==> Summary
🍺  /usr/local/Cellar/icu4c/55.1: 244 files, 65M, built in 4.9 minutes

2. install gollum

take@MacBook-Air ~/g/gollum> sudo gem install gollum
Password:
Building native extensions.  This could take a while...
Successfully installed charlock_holmes-0.7.3
Fetching: posix-spawn-0.3.11.gem (100%)
Building native extensions.  This could take a while...
Successfully installed posix-spawn-0.3.11
Fetching: gitlab-grit-2.8.1.gem (100%)
Successfully installed gitlab-grit-2.8.1
Fetching: gollum-grit_adapter-1.0.1.gem (100%)
Successfully installed gollum-grit_adapter-1.0.1
Fetching: rouge-2.0.5.gem (100%)
Successfully installed rouge-2.0.5
Fetching: stringex-2.5.2.gem (100%)
Successfully installed stringex-2.5.2
Fetching: sanitize-2.1.0.gem (100%)
Successfully installed sanitize-2.1.0
Fetching: github-markup-1.4.0.gem (100%)
Successfully installed github-markup-1.4.0
Fetching: gollum-lib-4.2.1.gem (100%)
Successfully installed gollum-lib-4.2.1
Fetching: kramdown-1.8.0.gem (100%)
Successfully installed kramdown-1.8.0
Fetching: rack-protection-1.5.3.gem (100%)
Successfully installed rack-protection-1.5.3
Fetching: sinatra-1.4.7.gem (100%)
Successfully installed sinatra-1.4.7
Fetching: mustache-0.99.8.gem (100%)
Successfully installed mustache-0.99.8
Fetching: useragent-0.14.0.gem (100%)
Successfully installed useragent-0.14.0
Fetching: gollum-4.0.1.gem (100%)
Successfully installed gollum-4.0.1
Fetching: mini_portile2-2.1.0.gem (100%)
Successfully installed mini_portile2-2.1.0
Fetching: pkg-config-1.1.7.gem (100%)
Successfully installed pkg-config-1.1.7
Parsing documentation for charlock_holmes-0.7.3
Installing ri documentation for charlock_holmes-0.7.3
Parsing documentation for posix-spawn-0.3.11
Installing ri documentation for posix-spawn-0.3.11
Parsing documentation for gitlab-grit-2.8.1
Installing ri documentation for gitlab-grit-2.8.1
Parsing documentation for gollum-grit_adapter-1.0.1
Installing ri documentation for gollum-grit_adapter-1.0.1
Parsing documentation for rouge-2.0.5
Installing ri documentation for rouge-2.0.5
Parsing documentation for stringex-2.5.2
Installing ri documentation for stringex-2.5.2
Parsing documentation for sanitize-2.1.0
Installing ri documentation for sanitize-2.1.0
Parsing documentation for github-markup-1.4.0
Installing ri documentation for github-markup-1.4.0
Parsing documentation for gollum-lib-4.2.1
Installing ri documentation for gollum-lib-4.2.1
Parsing documentation for kramdown-1.8.0
Installing ri documentation for kramdown-1.8.0
Parsing documentation for rack-protection-1.5.3
Installing ri documentation for rack-protection-1.5.3
Parsing documentation for sinatra-1.4.7
Installing ri documentation for sinatra-1.4.7
Parsing documentation for mustache-0.99.8
Installing ri documentation for mustache-0.99.8
Parsing documentation for useragent-0.14.0
Installing ri documentation for useragent-0.14.0
Parsing documentation for gollum-4.0.1
Installing ri documentation for gollum-4.0.1
Parsing documentation for mini_portile2-2.1.0
Installing ri documentation for mini_portile2-2.1.0
Parsing documentation for pkg-config-1.1.7
Installing ri documentation for pkg-config-1.1.7
Done installing documentation for charlock_holmes, posix-spawn, gitlab-grit, gollum-grit_adapter, rouge, stringex, sanitize, github-markup, gollum-lib, kramdown, rack-protection, sinatra, mustache, useragent, gollum, mini_portile2, pkg-config after 2543 seconds
17 gems installed

3. make folder and git init

take@MacBook-Air ~> mkdir gollum
take@MacBook-Air ~> cd gollum/
take@MacBook-Air ~/gollum> git init
Initialized empty Git repository in /Users/take/gollum/.git/

4. run

take@MacBook-Air ~/gollum> gollum
[2016-08-11 14:01:22] INFO  WEBrick 1.3.1
[2016-08-11 14:01:22] INFO  ruby 2.0.0 (2015-12-16) [universal.x86_64-darwin15]
== Sinatra (v1.4.7) has taken the stage on 4567 for development with backup from WEBrick
[2016-08-11 14:01:22] INFO  WEBrick::HTTPServer#start: pid=81909 port=4567

5. access

http://localhost:4567/create/Home