Add contribution guidance

Add CONTRIBUTING.md that points to the same document in chef-cookbooks
Add mention of the contribution document in the top of the README.md
Merge pull request #70 from claco/contributing

Merged automatically by jenkins after successful build test
ha clustering set from rabbitmq settings and clean up jcannava's bare tabs
Merge pull request #72 from rackerjoe/master

Merged automatically by jenkins after successful build test
Filter out Cinder VG from LVM

Without filtering out the cinder-volumes VG, LVM will happily
scan and import VGs defined on any block devices within /dev.

This commit adds a filter rule in /etc/lvm/lvm.conf which rejects
devices which match node['cinder']['storage']['lvm']['volume_group'].

Fixes DE253
Merge pull request #73 from DavidWittman/lvm-filter

Merged automatically by jenkins after successful build test