Export pluralization forms

When we export the csv for a locale we need to make sure we put the correct pluralization forms in.  For example, in english we just need ministers.one "minister" and ministers.other "ministers", but Arabic for example needs ministers.zero, ministers.one, ministers.two, ministers.few, ministers.many, and ministers.other.

When looking at keys from the source yml file we detect hashes that only contain pluralization forms and export the target locale forms instead.  If there is crossover (e.g. as with ministers.one and ministers.other between en and ar) we will copy the value across.

In passing I've regenerated all the locale files to include the correct forms.  It's a big diff and it seems to have moved keys around, but I don't think anything is missing.

For: https://www.pivotaltracker.com/story/show/45608311