Adding security option to SwiftMailer call. fixes #728

Configure the security option in emailer section of your ini file makes it possible to use for example gmail as SMTP service.
You need to specify for example:

[emailer]
host=smtp.gmail.com
port=465
security="ssl"
username="user@gmail.com"
password="password"
from="user@gmail.com"

in your ini for that.