Fix reverse() of 'password-reset-confirm' for email template.

The email template for resetting a password was still using "uidb36" for the
user ID, but Django has changed to "uidb64". This was causing an error when
users attempted to reset their password.

Fixes bug 3301.

Reviewed at https://reviews.reviewboard.org/r/5672/
Support custom HTTP methods for hosting services API calls.

This extends the API set for HostingService to allow subclasses to call
other forms of HTTP methods. For now, I've only added HTTP DELETE, which
will be used by an upcoming change.