exit with -1 on deploy error - #62

Does #54 not also give you the correct exit code?

Confirmed:

throw.js:

throw 'error!';

throw.sh:

#!/bin/bash
node ./throw.js
# will print nodes exit code, e.g. 0 for success
echo $?

throw.sh output:

error!
1

The exit code would have been 0 without the throw.

Closing this PR in favor of #54