Add documentation to bundle update group option
Merge pull request #3166 from dx7/master

Add documentation to bundle update group option
Stop building JRuby and Rubinius for now

[ci skip]
Test the newest 2.1 release [ci skip]
Use the Travis ramdisk for test installs
log space left after failure
Add a space characters to fix PullReview website errors
undo the failed ramdisk experiment
Merge pull request #3184 from DevRubySlippers/master

Add a space characters to fix PullReview website errors
Replace strings with defined constants
Merge pull request #3185 from meganemura/replace-with-defined-constants

Replace strings with defined constants.
Add space around operator '+'
Merge pull request #3190 from DevRubySlippers/master

Add space around operator '+'