Remove quotes around user name

The current version of `git-patch-to-hg-patch` leaves quotes around the user name part of the patch, but Mercurial doesn't use this when it makes its own patches natively, so the quotes show up in [commit logs][1], [on TBPL][2], etc.

This strips out the quotes.

[1]: https://hg.mozilla.org/try/rev/9e088baa9ed0
[2]: https://tbpl.mozilla.org/?tree=Fx-Team&rev=48a5e153526a