Revert "multiple -m"

This reverts commit cee12f6a2f.

This commit broke git-annex init run in a repo that was cloned from a
repo with an adjusted branch checked out.

The problem is that findAdjustingCommit was not able to identify the
commit that created the adjusted branch. It seems that there is an extra
"\n" at the end of the commit message that it does not expect.

Since backwards compatability needs to be maintained, cannot just make
findAdjustingCommit accept it with the "\n". Will have to instead
have one commitTree variant that uses the old method, and use it for
adjusted branch committing.

doc/todo/multiple_-m.mdwn

@@ -1,4 +1,2 @@
 git-annex sync etc -m should be able to be specified multiple times. In git
 commit, multiple -m can be used to make a multiparagraph commit. --[[Joey]]
-
-> [[done]]