core: Expose stop/start retry/delay configuration.

Expose stop/start retry/delay configuration to engine-config

This patch exposes the following values to engine-config:

FenceStopStatusDelayBetweenRetriesInSec (10)
FenceStopStatusRetries (18)
FenceStartStatusDelayBetweenRetriesInSec (10)
FenceStartStatusRetries (18)

The values in brackets are the default values so currently we are
waiting for the desired status for 3 min while pooling it each 10 sec
for 18 times.

There may be cases that those values should be customized and therefor
those values should be exposed to engine-config

Change-Id: I71c4af7b6d8fcdacaaff4abfec40b4fdf9cf5abf
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1147218
Signed-off-by: Eli Mesika <emesika@redhat.com>