Reduce the number of layers in the Configure menu

Originally, I was anticipating that Tor VPN would have a lot of settings, and designed the Configure tab with a deeper information architecture in mind. However now that we've collected most (if not all) of the settings we require for the VPN MVP, it's clear that:

1. Most of the apps settings are located within the "Connection" section, and the others are relatively light. This will be further exacerbated by the addition of "Exit location" to this section in #185.
2. At least one of these layers is superfluous – for example, bridge users should not need to tap three times just to navigate to Bridges (e.g. Connect > Connection > Bridges).