Rename GameInfo.txt to gameinfo.txt
Merge pull request #49 from ntgd/master

Fix 'gameinfo.txt' doesn't exist in subdirectory 'source-sdk-2013/mp/game/mod_hl2mp/'
Check in gitattributes for binaries.

Followup to @TheSeg's comments on 5f08baa.
Merge https://github.com/ValveSoftware/source-sdk-2013