Log blacklist hits to Special:Log

Adds a logBlacklistHit function function, which is callend whenver a new url
matches the blacklist. A new log type of "spamblacklist" is created, and is only
viewable by people with the "spamblacklistlog" userright. This is given to sysops
by default.

By default this is disabled, and is controlled by $wgLogSpamBlacklistHits.

Bug: 1542
Change-Id: I7b1ee2b3bb02b693d695bf66d157e2c33526c919
Merge "Log blacklist hits to Special:Log"