Update travis.yml

Update travis.yml to newer versions of Ruby and to check on OSX and Linux

.travis.yml

@@ -1,8 +1,19 @@
 language: ruby
+
+os: 
+  - osx
+  - linux
+      
 rvm:
-  - "1.9.3"
   - "2.0.0"
+  - "2.2.2"
+  
+before_install:
+  - if [ "$TRAVIS_OS_NAME" == "osx" ]; then rvm install 2.1 && rvm use 2.1 && ruby -v; fi
+  - if [ "$TRAVIS_OS_NAME" == "linux" ]; then sudo apt-get install --assume-yes --quiet gcc-multilib; fi
+  
 install:
   - bundle install
+  
 script:
   - bundle exec rake ci