Add Serializer and Deserializer for RangeSet

[Felk]

I had to write a generic serializer and deserializer for guava's RangeSet a while ago. While I did have a hard time understanding how exactly custom serializers and deserializers work, I managed to get it working. I believe that the code can be worked into an acceptable state with some feedback and help. For now, here's my slightly modified version of what we are currently using.

[cowtowncoder]

First of all, apologies for a slow follow up. Second: thank you for the contribution!

I'd be happy to merge this, but before I can do that there is one practical thing: we need a Contributor License Agreement (CLA), which is here:

https://github.com/FasterXML/jackson/blob/master/contributor-agreement.pdf

and the simplest way usually is to print it, fill & sign, scan, email to info at fasterxml dot com.
This only needs to be done once and then works for all contributions for any Jackson project.

On patch, one suggestion that might help: in findBeanDeserializer, JavaType can be used to figure out type parameters for Range, something like:

// note: `type.containedType(0)` also works for deserialization case where subtypes not supported
JavaType[] params = config.getTypeFactory().findTypeParameters(type, Range.class);
JavaType typeParam = (params.length == 1) ? params[0] : config.getTypeFactory().unknownType();

which would avoid needing to use createContextual(). I can make this change as well if you prefer.

Also: I think this would make sense to backport in 2.10 (or depending on timing, 2.9[.9]). I can do that.

[Felk]

Alright, I finally sent you the license contributor agreement. Sorry for forgetting about this.

I can make this change as well if you prefer.

That'd be easier, yes please

[cowtowncoder]

@Felk excellent, looking forward to getting this merged!