Add PNF simulator execution and cleanup as a BaseStep

Add PNF simulator execution and cleanup as a BaseStep

1. The simulator is the masspnfsim from integration project. Added as a git submodule.
2. The flow: build image, bootstrap simulator, run simulator, stop simulator,
remove simulator, remove image (only simulator).
3. Additionally trigger (sending a message to VES) is handled in pnf/utils.py. To send a request to VES,
vesip in settings.PNF_VES_CONFIG should be set to the one accessible from simulator container. Default one
(172.17.0.1) communicates with the machine the simulator runs at.
4. commonEventHeader's fields can be overridden in settings.py (here sourceName, reportingEntityName)

Issue-ID: TEST-278
Signed-off-by: Eli Halych <illia.halych@t-mobile.pl>
Change-Id: Id77dc8c517a30458abd81f2aadc416204be522b5