Ensure test coverage exit in Travis
Ensure test coverage exit in Travis

refs https://github.com/TryGhost/Ghost/commit/611e8b5634668ae7f908765532510cdf919d47cf

- looks like only grunt coverage won't tell Travis that the tests are finished
- second attempt

acburdine/Ghost,e10/Ghost,JohnONolan/Ghost,Kikobeats/Ghost,ErisDS/Ghost,Kikobeats/Ghost,TryGhost/Ghost,TryGhost/Ghost,ErisDS/Ghost,bitjson/Ghost,acburdine/Ghost,bitjson/Ghost,ErisDS/Ghost,kevinansfield/Ghost,janvt/Ghost,kevinansfield/Ghost,dbalders/Ghost,dbalders/Ghost,acburdine/Ghost,Gargol/Ghost,JohnONolan/Ghost,e10/Ghost,janvt/Ghost,Gargol/Ghost,chevex/undoctrinate,TryGhost/Ghost,JohnONolan/Ghost,dbalders/Ghost,Kikobeats/Ghost,kevinansfield/Ghost