Dashboard Module Updates

[sameleff]

1. Build functionality so that a user can modify the server update frequency from the dashboard
2. Consider developing a "config" page, so that the user can modify variables within the Active_Miners, Countdown, and/or Email_Notify tables from the dashboard
3. Modify the price history code so that the program only tracks the price history for those miners/coins that are currently active
4. Consider adding a split rewards column to the Active_Miners table so that the server code will automatically split rewards
5. Ensure all code is generalizable to support all coins from the major POW pools.