Enabled SMTP TLS and authentication options

Related: https://github.com/google/grr/issues/32
Weird, not sure where I would have lost the () since it was working for me when I was testing yesterday.  According to the python docs starttls() and sendmail() both call ehlo() if it hasn't already been called, but it certainly doesn't hurt anything to do it explicitly beforehand so I went ahead and put it in.