[CYB-103] Gallery Comments now register in back end

Front end Gallery Comments reflect in the back end as Comment Objects and Activity Objects

https://jira.ets.berkeley.edu/jira/browse/CYB-103
This should not be hard-coded to 1.  Instead, add an entry into db/seeds.rb for that one, and a line in config/locales/en.yml with the English text for the type (e.g., 'Post a comment on a gallery item').  Then get that score from the PointsConfiguration table.