Spam prevention

[pointerboy]

Regular users should have limit of 150 megabytes and a cool down of total 15 minutes between posting.

Email verification should be added too.

[pointerboy]

• Upload file size has been added and top of that, cool down for posts has been implemented

[pointerboy]

• Whitespace usernames are now blocked.

https://github.com/VanillaRemastered/ModHub/commit/8adcf4e57f89b2210468576fa04df21db079eccf