Update Travis settings for Rubinius

/cc @brixen

.travis.yml

@@ -1,16 +1,11 @@
-before_install:
-  - gem update bundler
-  - bundle --version
-  - gem update --system 2.1.11
-  - gem --version
 bundler_args: --without development
 language: ruby
 rvm:
   - 1.9.2
   - 1.9.3
   - 2.0.0
   - 2.1.0
-  - rbx
+  - rbx-2
   - ruby-head
 matrix:
   include:
@@ -20,6 +15,5 @@ matrix:
       env: JRUBY_OPTS="$JRUBY_OPTS --debug"
   allow_failures:
     - rvm: jruby-head
-    - rvm: rbx
     - rvm: ruby-head
   fast_finish: true

Gemfile

@@ -24,10 +24,4 @@ group :test do
   gem 'yardstick'
 end
 
-platforms :rbx do
-  gem 'racc'
-  gem 'rubinius-coverage', '~> 2.0'
-  gem 'rubysl', '~> 2.0'
-end
-
 gemspec