Disable automatic git commit of high water marks?

Opening for discussion!

I feel that automatically committing to git when running `rake ratchet` is a bad thing:

* As a developer, the commit log is something I should have careful control over. It seems intrusive for a tool to write to it.
* It adds noise the commit history - the change to the high water mark should be in the same commit as the code commit.
* There's no warning in the README that the gem does this, so it could be confusing/annoying for new users.

WDYT?