Add HHVM BetaFeature and wgPoweredByHHVM variable

To be deployed Saturday
enable BetaFeatures on meta and testwiki when HHVM goes live
HHVM FastCGI via port instead of a socket for beta features
disable refreshspecialpages when HHVM goes live
rebase master
database servers defined in LS
Merge pull request #389 from Orain/hhvm-beta

HHVM Beta Feature