email: Remove explicit ehlo() call

It won't work before we've connected to the server:

  Traceback (most recent call last):
    ...
    File ".\rss2email\email.py", line 145, in smtp_send
      smtp.ehlo()
    ...
  smtplib.SMTPServerDisconnected: please run connect() first

That makes sense ;).  If we want to call ehlo(), we should certainly
do it after the .connect() call succeeds.  Looking at the docs [1], I
don't think we need to call it at all:

  Unless you wish to use has_extn() before sending mail, it should not
  be necessary to call this method explicitly. It will be implicitly
  called by sendmail() when necessary.

We don't use has_extn(), and the EHLO should happen implicitly in
starttls [2]:

  If there has been no previous EHLO or HELO command this session,
  this method tries ESMTP EHLO first.

and send_message [3]:

  This is a convenience method for calling sendmail()...

via sendmail [4]:

  If there has been no previous EHLO or HELO command this session,
  this method tries ESMTP EHLO first.

[1]: http://docs.python.org/3/library/smtplib.html#smtplib.SMTP.ehlo
[2]: http://docs.python.org/3/library/smtplib.html#smtplib.SMTP.starttls
[3]: http://docs.python.org/3/library/smtplib.html#smtplib.SMTP.send_message
[4]: http://docs.python.org/3/library/smtplib.html#smtplib.SMTP.sendmail

Reported-by: Matt Bordignon <matthew@bordignons.net>
Signed-off-by: W. Trevor King <wking@tremily.us>