Bug 1002327 - Make the MMI code DSDS-aware r=etienne

(cherry picked from commit 7fe1f921349c8bee9b2514972b3882ee4ae1b221)

Conflicts:
	apps/communications/dialer/locales/dialer.en-US.properties
	apps/communications/dialer/test/unit/mmi_test.js
	apps/communications/dialer/test/unit/telephony_helper_test.js
Merge pull request #20955 from weigao123/push_master

Bug 1002327 - (master) add EventListener for mmi reply. r=Etienne.
(cherry picked from commit 8b742fde1be1226931eb198997994f4297375acd)
Merge pull request #21412 from gabrielesvelto/bug-1002327-v1.4-uplift

Bug 1002327 - v1.4 uplift