Use nodejs domain error handler instead of uncaughtError handle

See angular/protractor#876 (specifically [my
comment](https://github.com/angular/protractor/issues/876#issuecomment-57892972)). 
Cucumber uses the top level uncaught error handler to catch exceptions
caught by tests.  Refer commit
https://github.com/cucumber/cucumber-js/commit/9091129df4866cf705fb4ea7fb488f81e7cb96c2
and issue #51.  A good approach would be to wrap the test code
executions in try/catch blocks and use that exception instead of the
`uncaughtException` handler.  Another approach is to use the error
handler of a nodejs domain instead of the top level global
uncaughtException handler.  In this commit, I'm using the domain level
error handler approach.