Allows nodes to specify a ceph environment to search

If a server is in a different environment than the ceph mons, but
it still wants to connect to the ceph cluster, it can specify a
node['ceph']['search_environment'] attribute that matches the
ceph mons' node.chef_environment attribute.
This will enable the server to find the ceph mon nodes, register
for cephx keyrings, and create a working ceph.conf file
Merge pull request #112 from hufman/feature-custom-environment

Allows nodes to specify a ceph environment to search