Stabilize fb_deactivateWithDuration
Stabilize fb_deactivateWithDuration

Summary:
Deactivate application test is randomly failing, as we might return before application becomes active.
This happens, because it returns immediately after tapping application icon on springboard. We can fix this by simply waiting for springboard to disappear before returning control.
Closes https://github.com/facebook/WebDriverAgent/pull/222

Reviewed By: lawrencelomax

Differential Revision: D3644059

Pulled By: marekcirkos

fbshipit-source-id: 5694c73ba799465e0188cef82b12f56d1fb80610

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