Add support for DSDA

1. inform to clients whenever active sub change information
is received from telephony service.
2. inform local call hold status to RIL, whenever update on
the same is received.

Conflicts:
	src/java/com/android/internal/telephony/BaseCommands.java
	src/java/com/android/internal/telephony/Phone.java

Change-Id: If45351cce38c1ef0ea20ca45a821edd1fa594c82