Move nexus functionality to puppet-coe

Since the nexus puppetry needs more work
before it can be upstreamed, and the config
format will be changing in havana, this patch
moves the nexus puppetry into this module
and out of grizzly-manifests until it can
be re-done for havana in puppet-quantum.
Add module path to nexus template
Merge pull request #16 from michaeltchapman/move_plugin

Move plugin