Add an exit code to the test suite
Add an exit code to the test suite

By adding the exit code 1 (or any other non-zero exit code) `npm test`
will know the tests didn't perform correctly. This way it's easier to
know if pull requests are good or bad.

butchi/decodecodeJS,kittens/UglifyJS2,jchbh-duplicate/UglifyJS2,TrigenSoftware/ColaScript,istr/UglifyJS2,eth-srl/UnuglifyJS,davidbau/UglifyJS2,Venima/Test,vjeux/UglifyJS2,TurkeyFried/uglifyjs2-dist,rvanvelzen/UglifyJS2,tomByrer/UglifyJS2,shanaithal/UglifyJS2,hxford/UglifyJS2,VIVEKLUCKY1848/UglifyJS2,SpainTrain/UglifyJS2,digitalloggers/UglifyJS2,shelsonjava/UglifyJS2,eth-srl/UnuglifyJS,beni55/UnuglifyJS,dabretin/UglifyJS2,sahat/UglifyJS2,supriyantomaftuh/UglifyJS2,butchi/codedecodeJS,githuboflee/first,sielay/UglifyJS2,microlv/UglifyJS2,hychen/UglifyJS2,HankMcCoy/UglifyJS2,sebmck/UglifyJS2,GerHobbelt/UglifyJS2,Jeremy017/UglifyJS2,kemitchell/UglifyJS2,avdg/UglifyJS2,beni55/UnuglifyJS