Fixes usage inside a JAR

We are using this gem inside a JAR so that `jruby-complete.jar` can load our Ruby dependencies via "gems-in-a-jar". The problem is, that `jruby-scala-collections` does not have its extensions inside `spec.require_path`. Because of this, an error happens:

```
LoadError: no such file to load -- jar:file:/Users/nando/d/abstra/blueMountain/DSL/target/lib/gems.jar!/gems/jruby-scala-collections-0.1.4/lib/jruby/../../ext/dist/collections
          require at org/jruby/RubyKernel.java:1082
          require at jar:file:/Users/nando/d/abstra/blueMountain/DSL/target/lib/jruby-complete.jar!/META-INF/jruby.home/lib/ruby/shared/rubygems/core_ext/kernel_require.rb:53
          require at jar:file:/Users/nando/d/abstra/blueMountain/DSL/target/lib/jruby-complete.jar!/META-INF/jruby.home/lib/ruby/shared/rubygems/core_ext/kernel_require.rb:51
           (root) at jar:file:/Users/nando/d/abstra/blueMountain/DSL/target/lib/gems.jar!/gems/jruby-scala-collections-0.1.4/lib/jruby/scala_support.rb:3
```

The attached PRs attempt to solve this problem, and also make easier for Rubyists to compile the project.