sourceRouteThread: Encapsulate inotify thread

sourceRouteThread defined a main function for the inotify thread, but
the thread was created and started from supervdsmServer main function.
This couple these modules, expose module implementation details, and
make both sourceRouteThread and supervdsmServer harder to understand and
maintain.

This patch move inotify thread creation boilerplate from supervdsmServer
main function to a start function in sourceRouteThread module.  The
inotify thread main function is private now, unlikely to be used from
other modules by mistake.

A nice side effect is shortening the too-big-and-growing try-block in
supervdsmServer main.

Change-Id: I38e1d402ac1c1cd4de4c3e74910244b47e7977f0
Signed-off-by: Nir Soffer <nsoffer@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/22723
Reviewed-by: Assaf Muller <amuller@redhat.com>
Reviewed-by: Yaniv Bronhaim <ybronhei@redhat.com>
Tested-by: Yaniv Bronhaim <ybronhei@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>