JsonRollManager also now rotates after time (15min default).
The contents of the tarball are a single file that contains
one notification per file line.
The tarball is created after reaching a certain size or after
a fixed amount of time. Any working files are also tarball'ed
when the service restarts.
Change-Id: I6e9d620086cf24bc1468b638e7b148af7230e2ac