Add ruby 2.2 as a build target

MSP-11141

Ruby 2.2 was released, so ruby-head is now 2.3-dev.
Allow ruby-head to fail

MSP-11141

ruby-head (ruby-2.3.0-dev) is currently failing due to "LoadError:
cannot load such file -- test/unit/testcase", which is required by
activesupport-3.2.21/lib/active_support/test_case.rb.  activesupport
3.2.21 may not be ruby 2.3 compatible.
jruby-19mode is using jruby-9.0.0.0 so have to make jruby 1.7.X explicit

MSP-11141
travis-ci build fails for jruby-head, so allow to fail.

MSP-11141
Turn on fast_finish

MSP-11141

Now that there are allowed failures, turn on fast finish so the allowed
failures don't hold up the build.