Remove zmfix

zmfix's only purpose is to check the permissions of /dev/video* devices and correct them accordingly.
For a long time now, its possible to simply add the user apache runs on (often apache or www-data) to the video group like so:
```gpasswd -a apache video```
making zmfix not really needed anymore.

zmfix uses the setuid bit to run as root, which can be dangerous.
I can't see any reason why we need to keep zmfix.