More anti-spam measures

More spambots are finding the application page. Things in common: They all use
usernames following the syntax "LR<something>435", where "435" is a random
selection of 3 digits, and they all include HTML links in their notes. Maybe I
should disallow all HTML links, but we'll go with this for now.
Antispam fix

I was wrong, the usernames can include any number of digits at the end.
Merge pull request #19 from Sophira/application-nospam-2

More anti-spam measures