Allow user to set static page before saving

fixes #1350
- jQuery event.preventDefault() stops the user from selecting the checkbox
Fix wrong error message

closes #1466
- added status code for error object
- added test for frontend errors
Lowercase email address.

fixes #1498
Merge pull request #1489 from sebgie/issue#1466

Fix wrong error message
Merge pull request #1505 from halfdan/1498-lower-email

Lowercase email address.
Merge pull request #1353 from thgaskell/1350-static-page-checkbox

Allow user to set static page before saving
Correct the Markdown for emphasis
Merge pull request #1485 from Archanium/MinorIssues

Danish language file and a correction to Markdown modal