Added explicit Travis install for Coveralls.
Added explicit Travis install for Coveralls.

ryin1/textfeed,TwilioDevEd/clicktocall-flask,jgao1995/TextFeed,jgao1995/TextFeed,RobSpectre/Twilio-Hackpack-for-Heroku-and-Flask,RobSpectre/Mustached-Message-Service,TwilioDevEd/clicktocall-flask,RobSpectre/Twilio-Hackpack-for-Heroku-and-Flask,TwilioDevEd/clicktocall-flask