Enforce 2-digit dates in permalinks

fixes #1800

- changed permalink regex to require 4/2/2/slug
- changed url helper to enforce the same
- changed permalink toggle to set a specific state, this means the
  functional tests are independent again
- chnaged permalink toggle to wait for the settings page to load
- change as many frontend tests to not login as possible
Merge pull request #1802 from ErisDS/issue-1800

Enforce 2-digit dates in permalinks
Update Casper version on Travis