create a counter of anonymous notes in a cookie, read by new note controller to display an encouragement to contribute in the already existing anonymous warning if the anonymous visitor has already created at least 10 anonymous notes. Cookie deleted on log-in and sign-up after email validation
- Add preferred provider for authorization to login and signup pages.
To use, the 3rd party application would have to add `preferred_provider=...`
parameter to OAuth2 authorization request.
- Resize 3rd party provider icons
- Add "login to authorize" heading to login and signup screens
