Fixes rbx gems bundling on TravisCI

Conflicts:
	.travis.yml

Author: kurko

.travis.yml

@@ -7,9 +7,13 @@ rvm:
   - ruby-head
   - jruby-19mode
   - rbx-2
+  - ruby-head
 
 sudo: false
 
+install:
+  - bundle install --retry=3
+
 env:
   - "RAILS_VERSION=3.2.17"
   - "RAILS_VERSION=4.0.3"