BuildCommand: the default result is an error
BuildCommand: the default result is an error

Summary:
The current logic and implementation may result that in SimpleConsole (with `-c ui.superconsole=DISABLED`) a failure may be reported as a success first and then as a true failure. This can happen because `BuildCommand`:
1. assumes SUCCESS as an initial status
2. doesn't handle all exceptions
3. issues a build finished `event` in the finally block `params.getBuckEventBus().post(BuildEvent.finished(started, exitCode));`

This change ensures that for `buck build` success will be reported only if it was a real success

Reviewed By: ttsugriy

fbshipit-source-id: 2c40ce9

LegNeato/buck,kageiit/buck,nguyentruongtho/buck,SeleniumHQ/buck,JoelMarcey/buck,SeleniumHQ/buck,Addepar/buck,zpao/buck,shs96c/buck,shs96c/buck,romanoid/buck,rmaz/buck,JoelMarcey/buck,nguyentruongtho/buck,kageiit/buck,Addepar/buck,rmaz/buck,brettwooldridge/buck,facebook/buck,rmaz/buck,rmaz/buck,SeleniumHQ/buck,brettwooldridge/buck,brettwooldridge/buck,nguyentruongtho/buck,romanoid/buck,LegNeato/buck,shs96c/buck,SeleniumHQ/buck,facebook/buck,shs96c/buck,JoelMarcey/buck,brettwooldridge/buck,romanoid/buck,brettwooldridge/buck,SeleniumHQ/buck,shs96c/buck,shs96c/buck,rmaz/buck,JoelMarcey/buck,LegNeato/buck,rmaz/buck,Addepar/buck,JoelMarcey/buck,LegNeato/buck,shs96c/buck,Addepar/buck,rmaz/buck,nguyentruongtho/buck,zpao/buck,kageiit/buck,LegNeato/buck,rmaz/buck,SeleniumHQ/buck,Addepar/buck,Addepar/buck,Addepar/buck,shs96c/buck,kageiit/buck,romanoid/buck,romanoid/buck,JoelMarcey/buck,JoelMarcey/buck,rmaz/buck,facebook/buck,rmaz/buck,Addepar/buck,SeleniumHQ/buck,rmaz/buck,zpao/buck,shs96c/buck,facebook/buck,SeleniumHQ/buck,facebook/buck,LegNeato/buck,LegNeato/buck,romanoid/buck,shs96c/buck,zpao/buck,SeleniumHQ/buck,romanoid/buck,SeleniumHQ/buck,nguyentruongtho/buck,romanoid/buck,shs96c/buck,nguyentruongtho/buck,brettwooldridge/buck,brettwooldridge/buck,Addepar/buck,romanoid/buck,kageiit/buck,facebook/buck,LegNeato/buck,kageiit/buck,romanoid/buck,brettwooldridge/buck,facebook/buck,shs96c/buck,SeleniumHQ/buck,brettwooldridge/buck,nguyentruongtho/buck,LegNeato/buck,rmaz/buck,zpao/buck,Addepar/buck,zpao/buck,JoelMarcey/buck,zpao/buck,rmaz/buck,JoelMarcey/buck,Addepar/buck,JoelMarcey/buck,JoelMarcey/buck,brettwooldridge/buck,LegNeato/buck,LegNeato/buck,JoelMarcey/buck,romanoid/buck,shs96c/buck,LegNeato/buck,brettwooldridge/buck,brettwooldridge/buck,Addepar/buck,JoelMarcey/buck,brettwooldridge/buck,LegNeato/buck,romanoid/buck,SeleniumHQ/buck,romanoid/buck,Addepar/buck,SeleniumHQ/buck,kageiit/buck