Implements #95 Auto-close failed merge request

This version only uses intrinsic rather than object Booleans, and also only has the Auto-close feature within it, since that was my interest.  I will submit a separate request for the other similar feature.
@timols, @mc1arke 

Was there a reason you bumped the Jenkins version this is compatible with? Generally accepted practice in the Jenkins community is to use an LTS base version of Jenkins (e.g 1.580) to allow the plugin to be shown as compatible with both general releases and stable releases of Jenkins core, and I can't see a particular feature you're depending on here that wasn't in version 1.554.