Adding to the project

GeckoLib-Unofficial is lightweight and easy to install
You should download the dev version of the mod, put it in the lib folder of your mod (create it if it is missing)
And then include it in your build.gradle file

repositories {
    flatDir {
        dirs 'lib'
    }
}

dependencies {
    compile name: "geckolib-unofficial-1.7.10-1.x.x-dev" //The name of the geckolib file in the lib folder without ".jar"
}