Allowing ruby 2.1.0 to fail (for now)

as the rvm binary install is currently hosed.
Switching from 2.1.0 to 2.1 in travis matrix

as the 2.1.0 binary install is currently busted, but 2.1.1 is fine.
Merge pull request #401 from meatballhat/switch-from-ruby-2.1.0-to-2.1

Switch from ruby 2.1.0 to 2.1