Adds ability to confirm transactions over rpc

* New RPC method confirm_trans
* New RPC view on server side, confirm_transactions
* Database migration adding merged_type column for transactions
* New management function to fill in correlated merged_type for transactions
* Cleaned up some old management commands that were no longer needed
Adds payout amounts to merged mining tables
Removes new_block call and replaces with a scheduled task that fetches net stats for all currencies
* Removes coupling with powerpool and issue of duplicate tasks from multiple mining servers..
* Adds information on merge mined currencies, allowing addition of network stats for all networks
* Adds a basic network_stats api endpoint for viewing values easily