Revert "maint - Add temp workaround for travis ruby 1.8.7"

This reverts commit 34f10c9db724510ea584a6f44d989c60ae8ffe25.

The underlying issue was was fixed in gem 2.2.1.
Merge pull request #153 from richardc/travis_187_working

Revert "maint - Add temp workaround for travis ruby 1.8.7"