fixup f3e57ab

The issue from comment [1] has originally only been fixed in one
of multiple similar places.

Also pep8.

[1]: https://github.com/liqd/adhocracy/pull/499#discussion_r6410984
Update sass (3.2.11 -> 3.2.12)

I just got bitten by nex3/sass#941, which is fixed in version 3.2.12.
user-import additional-fields

This allows to provide additional csv columns in user_import
and use them for replacing {0}, {1}, ... in the invitation mail
Take came_from in login link into account if already logged in
Remove final adoption voting settings UI
pep8
fix plural
don't allow headings in user generated content to be as big as our own
fix settings nav well styling
use overlay format with htmlfill (fixes #580)
redirect startpage to instance
Allow to hide proposals navigation item
Merge pull request #586 from xi/feature-show-proposals-navigation

Allow to hide proposals navigation item
Merge pull request #583 from xi/feature-heading-size-in-UGC

don't allow headings in user generated content to be as big as our own
Merge pull request #585 from xi/feature-redirect-startpage-to-instance

redirect startpage to instance
Fix poll tiles if not in instance

This is a fixup of 3b97349dcefb652555aff99ee3cc7a3696af8680 and
0da4579e2e11c3d435d64c0e2473cb9298ebff68.
Fixup, in case there aren't additional fields
Merge pull request #582 from xi/feature-user-import-additional-fields

user-import additional-fields
Fix typo
fixup c83f765