Fix the lint script to ignore migrations files

The migrations files are machine-generated shite and linting them is an
exercise in futility. We're better off spending that time writing dubstep
remixes of popular ragtime songs, recording them on wax cylinders and
setting them on fire.

This fixes the lint script to ignore migrations files.
[bug 663524] Allow managing of the watch list
[bug 1058622] Add last_contribution_date to user index.
[bug 1058622] Show days since last activity in user search results.
[bug 1058622] Add days since last activity to top contributors page.
[bug 1058622][bug 1061433] Live indexing of users as they contribute.
Remove <img/> height and width attrs.
Fix NoneType error in watch list
Revert "[bug 1058622][bug 1061433] Live indexing of users as they contribute."

This reverts commit 4b1457bba06b77413cf8e6e4577311e30c3ca1ad.

This is causing a weird exception in tidings tasks. We need to
dig deeper.
Add AnonymousUser case to display_name test case
Tweak the __unicode__ method to be more resilient

We're seeing raven fall down when calling __unicode__ on Profile which
turns around and calls __unicode__ on User which for some reason doesn't
have a username.

This handles that case and if there's any exception thrown there, it
does a goofy thing and shows the profile id and the exception it kicked
up when doing unicode(self.user).

The purpose of this is to give us some information about what's going
on, but mostly to not create cascading errors which raven possibly
doesn't handle well.
[bug 1015345] Added friendly message for incomplete form submission during user login
Profile doesn't have an id column. pk is user_id.
[bug 1058622] Fix check for None