Merge branch 'android-geo' into 'master'

Don't start Tor in countries that are known to block it

See the javadoc for getCurrentCountry for details on how we get the country. In particular, it seems Google already has a hidden SystemService that does this, but we can't use it so we have to code our own. Luckily the solution I came up with independently yesterday almost exactly matches what they do.

Also, the hardcoded list of countries that block tor is incomplete; I will try to find a more complete list.