Do not send out any emails if .travis.yml does not exist on the branch we are building.
Do not send out any emails if .travis.yml does not exist on the branch we are building.

Addresses travis-ci/travis-ci#414

gavioto/travis-build,saucelabs/travis-build,Distelli/travis-build,gavioto/travis-build,akoeplinger/travis-build,paultcochrane/travis-build,lrowe/travis-build,vinaykaradia/travisBuild-clone,kidaa/travis-build,tmccombs/travis-build,wereHamster/travis-build,vinaykaradia/travisBuild-clone,Tiger66639/travis-build,vlamanna/travis-build,vlamanna/travis-build,wereHamster/travis-build,aceofspades/travis-build,craigcitro/travis-build,lrowe/travis-build,dirk/travis-build,jhass/travis-build,Acidburn0zzz/travis-build,will/travis-build,final-ci/travis-build,andyli/travis-build,craigcitro/travis-build,aceofspades/travis-build,tianon/travis-build,will/travis-build,tmccombs/travis-build,Joshua-Anderson/travis-build,aceofspades/travis-build,Distelli/travis-build,luoqii/travis-build,tianon/travis-build,JuliaCI/travis-build,a14n/travis-build,Joshua-Anderson/travis-build,saucelabs/travis-build,dirk/travis-build,Acidburn0zzz/travis-build,kevmoo/travis-build,will/travis-build,jhass/travis-build,final-ci/travis-build,Tiger66639/travis-build,kevmoo/travis-build,vlamanna/travis-build,a14n/travis-build,vinaykaradia/travisBuild-clone,Joshua-Anderson/travis-build,akoeplinger/travis-build,whip112/travis-build,paultcochrane/travis-build,kidaa/travis-build,JuliaCI/travis-build,whip112/travis-build,final-ci/travis-build,paultcochrane/travis-build,andyli/travis-build,wereHamster/travis-build,luoqii/travis-build