Override the default plural forms for a language on the server.
Pull request: https://github.com/zanata/zanata-server/pull/683
Implementations: Allow Zanata admin to override default plural forms in pluralforms.properties. - Changes in UI for admin to input new plural forms - Changes in HLocale table for new column, - pluralforms in HDocument should still has the highest priority, follow by data from HLocale, and finally pluralforms.properties.
Verified merge (master) at 062565c69a67bdfba201613c3a47a41a012a0edf