Handle wrong domains and dns errors
Send full HELO message
Implement "unsure" callback

If the reponse is neither 220, 250 or 550
tell the callback that we can't validate,
but we're not sure it's not a valid email
Handle connection timeout
Do a syntax check of the email before MX lookup
Remove all listeners once the callback is fired

This seems more like a workaround, since no other events should be
emitted afterwards, but they get emitted anyway.
Also tidied up the code to comply with jshint.
Remove useless logging
Fix regex check to not allow spaces
Handle connection error
Merge branch 'master' of git://github.com/nmanousos/email-existence
Remove trailing whitespaces
Merge pull request #5 from kunev/master

Several improvements