Add warbler to Gemfile and update gemspec. Depend on gollum-lib@master and adapters@master for dev purposes.

Gemfile

@@ -1,4 +1,12 @@
-source 'https://rubygems.org'
+if RUBY_PLATFORM == 'java'
+  gem 'gollum-rjgit_adapter', :git => 'https://github.com/repotag/gollum-lib_rjgit_adapter' # For development purposes
+  gem 'warbler'
+else
+  gem 'gollum-rugged_adapter', :git => 'https://github.com/gollum/rugged_adapter.git' # For development purposes
+end
 
+gem 'gollum-lib', :git => 'https://github.com/gollum/gollum-lib.git', :branch => 'gollum-lib-5.x' # For development purposes
+
+source 'https://rubygems.org'
 gemspec
-gem 'rake', '~> 11.2'
+gem 'rake', '~> 11.2'