Travis needs doc gems in order to run bin/yard

Author: mattbrictson

.travis.yml

@@ -20,7 +20,7 @@ sudo: false
 # original `cache: bundler` is a better option.
 cache: bundler
 
-bundler_args: "--binstubs --without documentation --path ../bundle --retry=3 --jobs=3"
+bundler_args: "--binstubs --path ../bundle --retry=3 --jobs=3"
 
 before_install:
   - script/clone_all_rspec_repos