Extended ssl-expiry-date to check for SHA1 phase-out restrictions

Google has announced that they will degrade user experience for
websites using SHA1 signed SSL certificates from Chrome 39 on:

- Certificates that are signed with SHA1 and are valid after
  January 1, 2016 will be show as insecure with a red HTTPS sign.
- Certificates that are signed with SHA1 and are valid after
  January 1, 2017 will be shown as insecure with a red HTTPS sign
  and will receive the mixed-content warning, wich has to be confirmed
  by the user.

The script has been made aware of that fact and will display if
either one of this conditions apply.