Improvements to Enterprise Linux family OSs.

* Install pygit from package
* Add Official Salt ZeroMQ 4 COPR repository

Note that Salt itself is assumed to already to be available to the system via yum, via EPEL for example

salt/gitfs/pygit2.sls

@@ -53,8 +53,7 @@ install-pygit2:
     - name: pygit2
 
 {% else %}
-# install from package
-# TODO haven't actually found a distro that has a good version to test
-# debian jessie will have libgit2-21
+{{ salt_settings.pygit2 }}:
+  pkg.installed
 
 {% endif %}