Adding support for PPS payout method

This commit changed a few things in the backend and classes code:

* Any <type>_PPS transaction does NOT need to be confirmed
* Queries updated for added <type>_PPS transactions
* Template updated to properly display these transactions

Cronjob

* Added pps_payput cron to run payouts based on worker submitted shares
* **IMPORTANT**: Can NOT be run with proportional_payout!

Addresses #70
properly format payout and round it