Add a zones.find(substring) method to return only zones whose
name matches that substring.

http://docs.rackspace.com/cdns/api/v1.0/cdns-devguide/content/list_domains.html
Merge pull request #1520 from minter/rackspace_domain_search

Allow selection of domains via substring
[rackspace|dns] added tests for zones.find
Set the User-Agent as Fog, to help differentiate from HP's CLI tools that have a vendored 'hpfog'
Merge pull request #1524 from mattray/User-Agent

Set the User-Agent as 'fog' instead of 'hpfog'