Previously enabling and disabling bandwidth testing in a certain order
lead to the parameter being included in the stream key that is saved to
disk, making it impossible to disable the bandwidth test later on.
By doing this properly and using string concatenation instead of
modifying (appending to) the key_ value this will no longer happen.
The message boxes that tell you that the browser is initializing or that
you're authenticating with twitch are annoying on startup. It makes
sense to do it in the settings/autoconfig dialogs where you sort of need
to know what's going on while waiting for it to connect, but on startup
it's not really necessary and can be kind of annoying.
