Fix some alignment.

The plastic implementation had some lines with an extra indent. Trivial change.
Merge branch 'master' into release-0.5.x
Add support for 2 factor authentication when logging in.

RBCommons will soon be getting 2 factor auth support, and this will
likely trickle down into Review Board at some point once things
stabilize. This change adds support for this when logging into RBTools.

After attempting to log in, the server may respond with an
X-ReviewBoard-OTP header. This is actually quite similar to the
X-GitHub-OTP header that GitHub uses. It indicates that a One-Time
Password is required, and what method the user is expected to use to
receive it. They are then prompted for that password. Once entering it,
RBTools will proceed as before, getting a cookie and using it for future
requests.