Have added some more options for pool configuration via the json config file

It is now possible to specify that a pool starts up disabled, or is removed completely from the pools available at runtime. This is useful because it allows the user to leave a large number of pools pre-configured in the json file, but only have them available or enable when required.

In addition, I have modified the displayed output in order to make it easy to determine which pool your are actually mining from, or which ones you are managing. This is done by showing the pool name in the managements lists, when it has been set. Have also added the port number to the 'mined from' pool at the top of the display (because some pools provide mining for multiple coins, only differentiated by the port number).