Bug 1016885 - Send a notification instead of displaying the dialer when receiving an unsolicited USSD notification r=etienne

(cherry picked from commit ddbf0e11b494fd9665545141485d0b70cab6d514)
Bug 1016885 - Always initialize the MmiManager before sending a notification r=etienne

(cherry picked from commit c664153cd702ae1db12a485e539bae88b9bdcdea)
Merge pull request #21538 from gabrielesvelto/bug-1016885-v2.0-uplift

Bug 1016885 - v2.0 uplift