Pass path to the config to instance_eval

This allows use of __FILE__ inside the eval'd config
Merge branch 'fix_ridley_202' into fix_berkshelf_808

Conflicts:
	lib/buff/config/ruby.rb
spec

Merge branch 'fix_ridley_202' into fix_berkshelf_808

Conflicts:
	lib/buff/config/ruby.rb
Merge pull request #6 from RiotGames/fix_berkshelf_808

Pass path to the config to instance_eval