ENHANCEMENT: significant speed improvement for many locales

Iterating over an array of locales and querying for each one causes tons
of unnecessary queries. This is especially evident when you get up to
hundreds of translations of a page. It makes the CMS admin UI insufferably
slow.  This is a little tweak to query for all of them at once instead of
individually.
Merge pull request #121 from jthomerson/pulls/cms_fields_performance_improvement

ENHANCEMENT: significant speed improvement for many locales