Make the "Manage pools" button executable again.
Make the "Manage pools" button executable again.

The button was never being set executable again because the Task run
by the button was blocking after configuring v1 pools.  This was fixed
by only creating tasks for >=v2 stakepools.  This could have also been
fixed by changing the v1 update task from 'new Task(() => {})' to
'Task.Run(() => {})' but this is a cleaner solution.

While here, make the newly configured pool the selected option in the
dropdown menu.

Fixes #258.

jrick/Paymetheus,decred/Paymetheus