Exit with an error code 1 if could not write a compiled JavaScript file or a source map

Currently CoffeeScript reports a success even if it failed to write a
compiled file to disk. This behavior confuses automated tools such as
test runners which may return false positives if a test failed to
compile because of a file lock.
Merge pull request #3592 from mmotorny/master

Exit with an error code 1 if could not write a compiled JavaScript file ...