WIP: Don't ask to accept the legal requirements when not logged in

Closes #811 (closed)

What does this MR do?

Don't ask to accept the legal requirements when not logged in.

How confident are you it won't break things if deployed?

Very!

Links to related issues

#811 (comment 298361654)

How to test

Test its gone when not logged in:

1. Without login go to https://foodsharing.de/?page=legal
2. Scroll down
3. There should be no "Nimmst du die Vereinbarung zur Kenntnis"

Test its there when logged in:

1. Log in
2. Update privacy policy by running in the terminal: ./scripts/mysql foodsharing "update fs_content set last_mod='2012-05-24 10:24:53' where id = x" where x is the id found in the debugbar under database (SELECT last_mod FROM fs_content WHERE id = x)
3. There should be "Nimmst du die Vereinbarung zur Kenntnis"

Screenshots (if applicable)

For screenshot see: #811 (comment 298361654)

Checklist

• added a test, or explain why one is not needed/possible...
• no unrelated changes
• asked someone for a code review
• joined #foodsharing-beta channel at https://slackin.yunity.org
• added an entry to CHANGELOG.md (description, merge request link, username(s))
• Once your MR has been merged, you are responsible to update the #foodsharing-beta Slack channel about what has been changed here. They will test your work in different browsers, roles or other settings