Run Chrome incognito in split mode

Since we now have an LRU cache, be very paranoid about the incognito <-> normal browsing boundary. This runs the extension in a separate process in incognito mode (no shared cache, etc.)

For details: http://developer.chrome.com/extensions/manifest/incognito.html

Upside: No cache leakage.

Downside: More memory usage when in incognito mode.


Signed-off-by: Nick Semenkovich \<semenko@alum.mit.edu\>