Add new RIL commands to read/write NV items and reset NV config.

Add new RIL commands and generic code cleanups.

The only changes required for OMA DM support are the
addition of five new methods in ITelephony.aidl for
reading/writing NV items and performing NV config and
radio resets (requires MODIFY_PHONE_STATE), along with
the new RIL request IDs in RILConstants.java.

Bug: 12864208
Change-Id: I958d2571580d98a49936ef2e6822e5ac086acbe2