Use `bootstrap` filter on forms

This will allow us to make forms far more consistent in the way they look and the way errors are displayed
Missing bootstrap imports in a couple of templates
Use inline filter on certain forms

Sometimes labels are sr-only
Change order of html display options
Tidy up inbox forms

* add breadcrumbs to form pages
* stop mixing up different bootstrap form classes
* primary buttons should be primary
Don't use btn-default as much

It tends to fade into the background, which isn't good for things we want to draw the user to, e.g. for backup tokens
Missed another form that needed inlining
Remove bootstrap mixins, we don't need them anymore
Custom two_factor forms no longer needed.
Liberation tests

However, they are completely useless because xstarmap doesn't work in Eager mode
Merge branch 'bootstrapform-issue-2'

Closes #2