Translatable activity messages and translatable date

This functionality was already included in 3fa43445bf5ddf031f7a685739b4c8f2c9ad67dd and 9bd45484d6679917e961a57b1bea4ea37a840f4a but it is not included anymore in the rtmedia.po ... Are you sure you also extract `_n()` when building the .po files?

P.S. can you please make sure that the phrase "Bulk Edit" finds its way into GlotPress?