closes#6826
- refactors the validation of facebook and twitter input field in `general.js` and `user.js` controller
- Example validations for facebook:
- `facebook.com/username` will be corrected to the full URL
- `user` will show error `Your Page name is not a valid Facebook Page name' for `general.js` and `Your Username is not a valid Facebook Username` for `user.js` as the username in facebook has to be at least 5 characters long
- `twitter.com/username` will be autocorrected to the valid facebook URL incl. the `username`
- Example validations for twitter:
- `twitter.com/user_` will be corrected to the full URL
- `user:99` will show error `Your Username is not a valid Twitter Username`
- `facebook.com/username` will be autocorrected to the valid twitter URL incl. the `username`
- updates both acceptance tests
- adds further validation for facebook pages in general settings and user. Submitting a url which incl. `/page/` or `/pages/` will now accept any username followed incl. further `/`.
- adds a custom transform `facebook-url-user` which will extract the username (if it's a facebook page, incl. `pages/`) to store only this in the backend
- uses the `twitter-url-user` transform now also for user
