webos_version.bbclass: Allow branch names with dots

:Release Notes:
Now we handle submissions/NN.<release>.MM which is MM-th tag along
branch @NN.<release> forked from tag submissions/NN which is on master.
Allow submissions/NN.<release>.MM.PP tags on branch @NN.<release>.MM
forked from tag submissions/NN.<release>.MM.

:Detailed Notes:
Allow multiple dots in the submission tag name.
Strip off the submission number along the branch (the field after the
last dot) to form the branch name. Improve comment in
webos_enhanced_submissions.bbclass to better describe this behavior.

:Testing Performed:
Only build tested.

:QA Notes:
No change to image.

:Issues Addressed:
[ES-571] Decide how to handle multiple levels of branched submissions
         of components
[BHV-9439] CCC: Fix submissions bbclasses to support pre-submission and
           multiple levels of branched submissions

Open-webOS-DCO-1.0-Signed-off-by: Martin Jansa <martin.jansa@lge.com>
Open-webOS-DCO-1.0-Signed-off-by: Nikolay Orliuk <nikolay.orliuk@lge.com>
Change-Id: Ib3cae0db156eccfcd736d55cd355bf921ee35021
Reviewed-on: https://g2g.palm.com/4949
Reviewed-by: Susan Montooth <susan.montooth@lge.com>
Tested-by: Susan Montooth <susan.montooth@lge.com>