Parse commitId and shortMessage of a commented out line in rebase todo

Parse commitId and shortMessage of a commented out line in rebase todo

A rebase todo file consists of regular non-comment action lines and
comment lines. In case that a regular action line has been commented out
(i.e. prefixed with a hash '#'), the RebaseTodoLine that is representing
this line should hold the values for commitId and shortMessage even
though it's a comment line. This allows to switch between comment and
non-comment easily even after the file has been persisted and reread.

Change-Id: I56ec2ba08eaf3772e2d74d937dd496209a744d4b
Signed-off-by: Tobias Pfeifer <to.pfeifer@web.de>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>