WAPPushManager, WAP Push over SMS message handler

The WAPPushManager is a new, optional service for handling WAP Push
over SMS messages.  This service allows a carrier to designate a high
priority handler for specific WAP Push over SMS messages without
affecting other WAP Push over SMS, binary SMS, or SMS text messages.
It is also optional, so that it can be configured out of the target
image resulting in no change in the WAP Push over SMS handling
behavior compared to the current AOSP.

- This patch contains the WAPPushManager itself, the associated test
  code, and the modifications to telephony to use the WAPPushManager.

Change-Id: I4f7fb5b68fc666da9bdeeea525e8797ae317e4b5