Update Travis settings for Rubinius

/cc @brixen

.travis.yml

@@ -1,8 +1,3 @@
-before_install:
-  - gem update bundler
-  - bundle --version
-  - gem update --system 2.1.11
-  - gem --version
 bundler_args: --without development
 language: ruby
 rvm:
@@ -14,11 +9,10 @@ rvm:
   - jruby-18mode
   - jruby-19mode
   - jruby-head
-  - rbx
+  - rbx-2
   - ruby-head
 matrix:
   allow_failures:
     - rvm: jruby-head
-    - rvm: rbx
     - rvm: ruby-head
   fast_finish: true

Gemfile

@@ -27,8 +27,4 @@ platforms :mingw, :mswin, :ruby do
   gem 'yajl-ruby', '~> 1.0', :require => nil
 end
 
-platforms :rbx do
-  gem 'rubysl', '~> 2.0'
-end
-
 gemspec