Fixed:  Listings that are super-duped run out of memory

Some listings get duped dozens of times.  Building the string of dupes
actually can blow through PHP's memory so we now just truncate the dupe
list after about 4 items.
Fixed issue#50: Craigslist not returning results for multiple terms
Email:  Added pass-through support in INI file for PHPMailer SMTP settings

You can now specify the SMTP properties to be passed directly to
PHPMailer in the INI file under [email]
[email.smtp]

For the list of properties to use, refer to the PHPMailer documentation
on https://github.com/PHPMailer/PHPMailer/blob/master/README.md.

If there are no SMTP settings specified, job_scooper uses Sendmail
instead of SMTP.
ZipRecruiter:  Cleaned up Job IDs for ZipRecruiter posts