JJB integration: Return code from pybot shall be ignored

JJB integration: Return code from pybot shall be ignored

Jenkins starts scripts in "Execute sheel" as bash -xe <path>
so any non-zero return code breaks the script on the spot.
Pybot commands can return non-zero return code just when
a critical test case fails.
But in that case, the rest of script is now skipped,
including the useful karaf.log download.

This change adds "|| true" hack to make return code zero.
Also, single and cluster scripts have the formatting
of the pybot line unified now.

Change-Id: I4a9dcf937ca4caca43ee9dfdfeda67ca172be608
Signed-off-by: Vratko Polak <vrpolak@cisco.com>