Returning error response, when bundleId is missing in start session command
Returning error response, when bundleId is missing in start session command

Summary: Closes https://github.com/facebook/WebDriverAgent/pull/163

Differential Revision: D3333430

Pulled By: marekcirkos

fbshipit-source-id: 5e7e60025d46795e2920fe94982aa789f3de913a

Gogle/WebDriverAgent,b1ueshad0w/WebDriverAgent,b1ueshad0w/WebDriverAgent,qa-dev/WebDriverAgent,b1ueshad0w/WebDriverAgent,qa-dev/WebDriverAgent,b1ueshad0w/WebDriverAgent,Gogle/WebDriverAgent,PiranhaTeam/WebDriverAgent,qa-dev/WebDriverAgent,zenzhu/WebDriverAgent,riccoyu/WebDriverAgent,PiranhaTeam/WebDriverAgent,calabash/WebDriverAgent,Gogle/WebDriverAgent,drptbl/WebDriverAgent,riccoyu/WebDriverAgent,drptbl/WebDriverAgent,PiranhaTeam/WebDriverAgent,Gogle/WebDriverAgent,PiranhaTeam/WebDriverAgent,ymin/WebDriverAgent,PiranhaTeam/WebDriverAgent,riccoyu/WebDriverAgent,riccoyu/WebDriverAgent,ymin/WebDriverAgent,qa-dev/WebDriverAgent,ymin/WebDriverAgent,rafael-chavez/WebDriverAgent,drptbl/WebDriverAgent,zenzhu/WebDriverAgent,zenzhu/WebDriverAgent,calabash/WebDriverAgent,calabash/WebDriverAgent,ymin/WebDriverAgent,rafael-chavez/WebDriverAgent,rafael-chavez/WebDriverAgent