(#2916) - test android by avoiding CORS

Hopefully this should pass. Saucelabs' Android setup is messed up, because they just don't seem to allow CORS at all. So I work around it by having an AVOID_CORS option and an express proxy to CouchDB running on the same port.

Android 4.3 and below seems to just have WebSQL disabled, because it throws a DOM Exception 18 (security error).