Glance rbd backend support

Added glance rbd backend support.
Merge pull request #101 from bodepd/glance

Glance rbd backend support
Added rjil::openstack_zeromq

NOTE: this has a dependancy on PR #1 of jiocloud/openstack_zeromq.

1. Added rjil::openstack_zeromq class
  a. This class accept consul dns names for various openstack services
  b. Resolve SRV records for the names given
  c. Add /etc/hosts entry for the hostname part of fqdn, so that the hostnames
      can be resolved.
  d. Call ::openstack_zeromq with an array of hostnames striped from fqdn.

2. Added a function service_discover_dns
  This function accept a dns name and return type and return accordingly
   Valid return types are:
    name: Return array of names
    ip:   Return array of IPs
    both: Return a hash of both names and ip.

3. Added function easy_host
  This function accept simple hash value with name and ip and add appropriate
    /etc/hosts entry.
  Depending on the name it add host alias also (depening on whther the input is
  fqdn or just a hostname.

4. Added basic spec tests.

Note: Unit tests to be improved. Currently There are couple of things due to
which I wrote basic tests.
  1. Need to see how to mock dns lookup.
  2. Need to know how to test parametes for functions being called.
  3. While using puppet_spec/compiler, getting error (no such file).
     Need to fix that or to use any other method to test easy_host.