Update extension icon when proxying to others

Ran grunt test.

Icon updates correctly when you start proxying, stop proxying, start providing (giving) but not when you stop providing. Should work once rtcToNet (in RemoteInstance) knows to close when corresponding socksToRtc is closed. 
I couldn't figure out how to get rid of it because of one call in src/chrome/extension/scripts/chrome_connector.ts (line 163). I'm not really sure if the call can be moved somewhere, and if it cant be moved, do I need to add a stopProvidingProxy call in the disconnect handler?