1. Add Apache 2.0 license.
2. Added anchors to sections in README
3. Added instructions to use AAR file in README
4. Add README section to for requesting read-write access. This was already present in code but not documented.
5. FileXInit.isUserPermissionGranted() returns false if global root directory is deleted and replaced with a file of same name.
6. Fix onResult() not being called if user denied read-write permissions or denied selecting a root directory.