Upgrade minitest to v5.4.0
Remove the yajl-ruby gem because it not used
Upgrade coderay to v 1.1.0
Upgrade grit to v2.5.0
Update haml to v4.0.5
Upgrade thin to v1.6.2
Small bug fix for the merge notifier

The notifier would notify about an error if it was passed an empty hash
of change counts. Probably not a case which will ever come up, but it
was not the desired behavior.

Fixed so that the empty change hash will give no notification, as
expected.
Merge pull request #91 from acant/gem_updates

Simple Gem updates and a small bug fix