Return browserify bundle instead of generating the bundle

I've made the change and fixed a bunch of tests, but there are some that I couldn't. They are all using run.js in order to run the command line version of mochify.

~~The problem resides in the return code of the operation, it is always 0-ok. I believe it is because what will fail now is the bundle but not the process itself.~~

I figured out the problem in cmd.js. Anyways I'm still failing since ```.bundle(cb)```  doesn't call ```cb``` if the tests fails, only if the bundle fails. I need to catch this case somehow so it is possible to ```process.exit(1)```

Can you please have a look?
Thanks
F
I've updated cmd.js so it doesn't exit when in watch mode. I wasn't able to test when the watch flag is on since the process never ends, therefore all the attempts to assert from the test results in a timeout. If you have an idea how to workaround that I can give another try for that special case