Clarify the meaning of the globe icon used for exit location

The earth icon, to choose your exit location, is a confusing icon. It's small and hard to recognize (is it a Tennis Ball, or someone from the Amercas looking at the world?) also lacks a text label.

User research findings

During the usability tests of 0.6.2 (tpo/ux/research#69), 2/6 participants commented on this issue as well.

• It's a best practice to always add a label to icons. « Universal icons are rare. To help overcome the ambiguity that almost all icons face, a text label must be present alongside an icon to clarify its meaning. »
• The unclear mental model on how Tor works didn't help either, so maybe we should solve this issue together with other issues related to the network model.

Ideas

• Make the icon clearer: swap icon? increase size?
  • VPNs use flag and location names.
• Add a label to the icon?