Bug 977547 - JSHint fixes for Search r=mcav
Merge pull request #16712 from KevinGrandon/bug_977547_jshint_search

Bug 977547 - JSHint fixes for Search r=mcav
Bug 947180 - [DSDS][Message] Message notification informs of SIM r=schung

This shows a prefix in the message notification when we are in a Dual SIM
scenario.

This also introduces an utility function to find the correct SIM index and to
detect the Dual SIM scenario.