run-local-project: on exception, immediately return non-zero return code

This makes sure that 'lein cljsbuild test' exits without 30 second delay.
Introduce TestsFailedException
Throw TestsFailedException when tests fail
Do not print stacktrace for TestsFailedException
Merge remote-tracking branch 'hsalokor/master' into 0.3.1
Reformat things consistently with surrounding code.
Merge remote-tracking branch 'hsalokor/topic/suppress_stacktrace_on_test_failure' into 0.3.1

Conflicts:
	plugin/src/leiningen/cljsbuild.clj