Put Optional() validator back in, reset IP regexes to what they were before

Seems that a pattern on a field on the front end, is only checked if the field contains something, to have fields required on the front end, the required attribute has to be added in.

So... I put the Optional() validators back on the WTForm fields, reset the IP address regexes on the backend to what they were on Claudyus' repository, removing the ((..)|) around the regexes I added a few commits ago, and added the required attribute on fields that are required (utsname, and rootfs)

Also make link and macaddress IP address the same on the backend and the front end (for the mac address, the frontend regex was better, so I kept that one)