Disallow foodsharing email addresses for password restore and remove addresses from bounce list

Closes #744 (closed) and #756 (closed)

What does this MR do?

Disallows email foodsharing addresses when changing the address in the settings. With this people cannot be locked out when forgetting and resetting their password.

Also moves some of the strings to the translation file.

Before sending the confirmation email the address will be removed from the bounce list.

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

Quite sure, should work.

How to test

Steps a reviewer can take to verify that this MR does what it says it does e.g.

1. Checkout branch locally
2. Login as foodsaver
3. Go to personal settings
4. Try to change your email address to e.g. something@foodsharing.network
5. An error message should appear

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