Removed reference to Express's configure function which was previously optional, and is now removed in Express v4.
Removed reference to Express's configure function which was previously optional, and is now removed in Express v4.

I tested fix against Express v2.5.1, v3.4.8, and v4.0.0-rc2

Fixes issue #49

thiagocarreno/easyrtc,cristiancvanega/easyrtc,logoff/easyrtc,charlesAtNctu/easyrtc,nmai/easyrtc,priologic/easyrtc,charlesAtNctu/easyrtc,priologic/easyrtc,xirsys/easyrtc,chaudhary4k4/easyRTC,ash24mish/easyrtc,Hocalwire/easyrtc,hthetiot/easyrtc,chaudhary4k4/easyRTC,mauricionr/easyrtc,mauricionr/easyrtc,udayshankar3/nodeapp,bgawande/easyrtc,priologic/easyrtc,hthetiot/easyrtc,bradparks/easyrtc,ash24mish/easyrtc,Sylaps/easyrtc,bradparks/easyrtc,udayshankar3/nodeapp,Hocalwire/easyrtc,linagora/easyrtc,ash24mish/easyrtc,logoff/easyrtc,bgawande/easyrtc,nmai/easyrtc,cristiancvanega/easyrtc,bgawande/easyrtc,linagora/easyrtc,ash24mish/easyrtc,thiagocarreno/easyrtc,Sylaps/easyrtc,Hocalwire/easyrtc,thiagocarreno/easyrtc,hthetiot/easyrtc,priologic/easyrtc,Hocalwire/easyrtc,nmai/easyrtc,bradparks/easyrtc,cristiancvanega/easyrtc,mauricionr/easyrtc,logoff/easyrtc,xirsys/easyrtc,Sylaps/easyrtc,charlesAtNctu/easyrtc