Handle ability to activate background jobs

Thanks for this great tool - It really saves an impressive amount of time in the development of CloudCode. I'm not sure anyone has taken it to the next step, but it seems it could enable automated local unit and integration testing too. Stubbing out the Parse classes would be the next logical step.

This pull request add the ability to execute background jobs. All the functionality was there to define background jobs, but no way to execute them for testing (unless there is some other non obvious way to do it?). 

Also fixed a couple of typos and unclear messages.