use z as prefix for CI qualifiers to make them always the newest

P2 uses the full version qualifier to find out which bundle is newer.
'z<timestamp>' is always greater than 'Mx_<timestamp>' or a simple
timestamp, hence the CI build will always be recognized as newer even if
there is a milestone or release with the same timestamp.

Change-Id: I3626faa20cdd8b270dff6edffe84074279b20dc7
1 file changed