Add storage for submodule bookkeeping
Revert "Initialize branches specified in the create repository ruleset."

The reverted commit looks very wrong to me.  The "created" member is
very badly named, but it is supposed to represent the SVN revision in
which a branch was created.  By setting it to 1, it is never updated
in this line:
https://gitorious.org/svn2git/svn2git/blobs/master/src/repository.cpp#line213

This reverts commit d257d0e911a18d2c248fc44328917ef209542a95.
Add scaffolding for handling submodule changes