git-p4: Clean up git-p4 submit's log message handling.
git-p4: Clean up git-p4 submit's log message handling.

Instead of trying to substitute fields in the p4 submit template we now simply
replace the description of the submit with the log message of the git commit.

Signed-off-by: Simon Hausmann <088e16a1019277b15d58faf0541e11910eb756f6@lst.de>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git