Need an SMTP server timeout

[mcoles]

Doing some testing trying to use Mandrill as an SMTP server, I found that VizAlerts was stalling because traffic was being blocked internally to external mail services. Should set a configurable timeout in vizalerts.yaml so that we don't wait for forever if that happens.

[mcoles]

vizalert\emailaction.py , line 114:

    server = smtplib.SMTP(config.configs['smtp.serv'], config.configs['smtp.port'], timeout=**somevalue**)

[AirCooledNut]

Along with a nice, user-friendly error message ;-)