simplify test for image size option
bump 1.6.0
Add temporary workaround for failing build on Ruby 1.8.7
Rubygems broke builds on Ruby 1.8.7:

travis-ci/travis-ci#1793
rubygems/rubygems#763

This patch is a temporary workaround until rubygems is updated.
fix broken travil YML. derp.
Add Rubinius and 2.1.0 to Travis config.  Add Rubinius gems to Gemfile.  Remove jruby-openssl from Gemfile and README.  Update JRuby version in README to 1.7.9
Merge branch '1-6-stable'

Conflicts:
	CHANGELOG.md
Merge pull request #143 from petergoldstein/feature/add_2_1_0_and_rbx

Travis - Add Ruby 2.1.0, Rubinius