Exit with error code on any script errors

[cmc333333]

We're running into the same issue as described in jasmine-contrib/grunt-jasmine-runner#20

Running $ grunt jasmine, we get:

Running "jasmine:all" (jasmine) task
Testing jasmine specs via phantom
>> TypeError: 'undefined' is not an object (evaluating '$('#sub-head')[0].offsetTop') at
[snip snip]
...............
15 specs in 0.15s.
>> 0 failures

Done, without errors.

The execution has the error code 0, so external tools (e.g. Travis) don't see than an error has occurred.

[Igloczek]

@jsoverson I don't get why it's closed without any comment, but I'm facing the same issue and looking for some solution.