Ability to require that the source content be at the same domain as the
page which loaded the player
   - Added VideoJSModel.validateRestrictedSrcDomain method which if
restrictions are enabled checks Security.pageDomain against the src URL
   - Added calls to validateRestrictedSrcDomain in relevant src loading
areas
   - Added VideoJS.RESTRICT_SRC_DOMAIN defined via CONFIG
   - Added check of grunt option restrictSrcDomain which defines CONFIG
command option