Bug 913360 - Hard-coded en-US plural in threads with multiple recipients r=borja

Chirurgical patch to use the normal l10n mechanism for plural forms.
Only for v1-train, we already do this on master.
Merge pull request #11720 from rexboy7/fix-bug906981

Bug 906981 - [Lockscreen] Check if mozTelephony exists for desktop build(cherry picked from commit b5a447c963ec165ffb7102c9a53c00d51f10b3a2)
Merge pull request #12033 from lodr/bug-914117-fixing-no-sms-topup-scenario

Bug 914117 - Checking for top up senders existence before parsing
r=jmcf(cherry picked from commit f941936f4570b37445be2a41dbb40bcd0d100cfd)
Merge pull request #12083 from lodr/bug-914636-handling-messages-from-widget

Bug 914636 - Fixing message handler
r=arcturus(cherry picked from commit 986ad07aad596c5006c229e5f2304783f601c4cc)
Merge pull request #11794 from mcirlanaru/bug_908329

Bug 908329 - [Keyboard] Update alternatives menu width logic. r=@davidflanagan(cherry picked from commit 0d226095c9486e45d662d6f5da8ac807e04e17b8)
Merge pull request #12106 from jaoo/911874

Bug 911874 - [zffos1.1][P2][MMS] The DuT does not support size of 500 KB for MMS for one fo the mcc/mnc of Mexico operator. r=kaze(cherry picked from commit f99ee54d9b8a5b182a987ff012e690f1269ecb43)
Merge pull request #12024 from changyihsin/wifiQuickSetting

Bug 908989 - [Buri][WIFI]Can't turn on/off wifi from pull down state bar r=alive(cherry picked from commit 416b129d78addce75f323ebaf286d13e6ff97063)
Bug 907161 - Remove UA override for domains week starting 2013-08-19 (v1-train version)

This was originally 54cca89fa365d8f413fe73f6ec52b210655a60e4
Merge pull request #11988 from julienw/913360-plural-forms

Bug 913360: plural forms for recipients