Add an option to use common terms for comments.

If the option adhocracy.comment_wording is set to True, the terms
"comment" and "comments" are used instead of "argument" and
"discussion".
Merge pull request #346 from wawe/option-comment-wording

Add an option to use common terms for comments.
Update translations (see #346 for context) (Fixes hhucn/adhocracy.hhu_theme#223)
Fix a German translation (Fixes hhucn/adhocracy.hhu_theme#264)
Make comment_wording variable affect additional translations.

Use 'Add argument' instead of 'reply' for comment_wording = False.
Add/Update German translations regarding replies.
Merge pull request #347 from wawe/option-comment-wording

Different translations for 'reply' based on comment_wording
Set CSRF token in registration form
Lock down and clarify nopassword
Convert INSTALLATION to rst
i18n: Upgrade Italian translation
Correct links to INSTALLATION.md
Make append_member_and_format consume kwargs

Commits 42e03d2796f95ff1a1220277d5efd6e123073191 and
604e2358ee706c9164e964bdf31aefe06bb063c8 accidently called
append_member_and_format with kwargs indirectly.

This commit simply makes the function accept kwargs and do nothing with
them.
Update README (RabbitMQ -> Redis)
fix typos in docstrings
pep8
Remove unneeded method
Make FakeJob work again

This allows to run Adhocracy without configuring Redis
Better debug message in FakeJob case
Add configuration option to disable background processing