Add manifest even though #ThisIsABadIdea

There are already 2 things I’ve had to set in Cordova’s generated
AndroidManfest.xml:

- minSdkVersion=18, because the android-minSdkVersion option you can
apparently use in config.xml doesn’t seem to work
 - uses-feature android.hardware.bluetooth_le

Even though this file is generated I’ve had success w/ it not whacking
either change. So now committing it, just in case it does start
whacking.