Add hhvm checking
Add hhvm checking

I am curious to see if it works.
See http://blog.travis-ci.com/2013-12-16-test-php-code-with-the-hiphop-vm/
nwsw/Elkarte,StealthWombat/How-to-fork-an-Elk,nwsw/Elkarte,emanuele45/Dialogo,wizardaf/Elkarte,StealthWombat/How-to-fork-an-Elk,nwsw/Elkarte,StealthWombat/How-to-fork-an-Elk,Spuds/Elkarte,elkarte/Elkarte,wizardaf/Elkarte,interlab/Elkarte,Spuds/Elkarte,StealthWombat/How-to-fork-an-Elk,emanuele45/Dialogo,joshuaadickerson/Elkarte2,wizardaf/Elkarte,joshuaadickerson/Elkarte2,elkarte/Elkarte,emanuele45/Dialogo,interlab/Elkarte,Spuds/Elkarte,elkarte/Elkarte,interlab/Elkarte,wizardaf/Elkarte,joshuaadickerson/Elkarte2,joshuaadickerson/Elkarte2