Added quite much stuff, listed in description

Added progess bar for current song time, with labels for accurate time
and total song length.
Added more descriptive tooltips for Spotify control checkboxes.
Added labels to show if Spotify or Web Helper are running/not running
next to the control checkboxes.
Added try-catch when attempting connection.
Added more descriptive error message if connection fails.
Made "Retry connection" button show if connecting fails with an
exception.