Fix URL names and targets for the password reset flow.

The password reset functionality regressed when we switched over to django's
bundled implementation (instead of our own). We had a couple earlier fixes to
this, but there were still some small errors. This makes it so that all the URL
names and view functions match up exactly as they should.

Testing done:
Went through the whole password reset flow and verified that it works.

Fixes bug 3358.

Reviewed at https://reviews.reviewboard.org/r/5856/