(bug 58943) Archivebot: create unit tests for Timestripper

Unit tests for Timestripper. Initialization moved to
def setUp to prevent import deadlocks.

Change-Id: I521cdd0f5258c41e7e4d77e89ff616ed789b7824
Original-Change-Id: I12414e24f048ab7919a66be6c9b41e5b8e8c0c13
Merge "(bug 58943) Archivebot: create unit tests for Timestripper"