ShortpagesPage: corrected case

In MW autoloader "case correcting" behavior was disabled as it costs performance when using more then one autoloader. One case was not properly addresed - special page ShortpagesPage. Correcting this now.
Special pages: corrected case
Special pages: corrected case
Merge pull request #1028 from Wikia/release-170-fix-ShortpagesPage

ShortpagesPage: corrected case