Provide Don't Ask Again Option for Doze WhiteListing
If Briar is not whitelisted for doze exceptions, we show a dialog each time NavDrawerActivity is opened until the user whitelists us.
We should provide a "don't ask again" checkbox for users who value battery life more than connectivity.
Also check if we are whitelisted not in NavDrawerActivity but
- At startup, check whether we're whitelisted and if not, ask the user to whitelist us
- When the device enters doze (ACTION_DEVICE_IDLE_MODE_CHANGED), check whether we're whitelisted and if not, sign out