Implementation of Remote-SIM.

Design doc http://shortn/_GG690j15js

1. Modified SmsManager to send message thru Bluetooth if the subscription
   is for a Remote-SIM.
2. Added new column 'subscriptionType' to SubscriptionInfo.
3. SubscriptionManager:
  a. Added new constants for Local SIM and Remote SIM
  b. Added hidden APIs to add/remove Remote SIM subscriptions

Bug: 112321331
Test: tested manually and w/ unittests
Change-Id: Ib15553a806691a258fc00f7aaf812b8a9d49c2e9