remove rubinius support, it only causes problems

Author: mpapis

.travis.yml

@@ -10,8 +10,5 @@ rvm:
   - 1.9.3
   - 2.0.0
   - jruby-19mode
-  - rbx
 matrix:
-  allow_failures:
-    - rvm: rbx
   fast_finish: true

Gemfile

@@ -11,11 +11,4 @@ group :development do
   gem "redcarpet", :platforms => [:mri_20]
   gem "simplecov", :platforms => [:mri_20]
   gem "coveralls", :platforms => [:mri_20]
-
-  # rubinius support
-  gem "rubysl-json",      :platforms => [:rbx]
-  gem "rubysl-mutex_m",   :platforms => [:rbx]
-  gem "rubysl-open3",     :platforms => [:rbx]
-  gem "rubysl-singleton", :platforms => [:rbx]
-  gem "rubysl-stringio",  :platforms => [:rbx]
 end