Originally I was thinking it might be useful to store counter objects in the
tags, but that adds a bunch of complexity to the serialization layer and tag
users can just get the existing tag, and then increment the value themselves.
Testing Done:
Ran the unit tests.
Reviewed at https://reviews.imfreedom.org/r/2053/
PidginandFinch:ThePimpin' Penguin IM Clients That'reGoodfortheSoul
Thisfileintendstolistallchangestolibpurple,Pidgin,andFinch's public