Bug 1050816 - update about:customizing header, r=jaws

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extra : rebase_source : 02ddd23ac0bcebc2ada811f30b63a9b784fe7270
Bug 991757 - add telemetry for the context menu, r=mconley,bgrins,f=bwinton
Bug 1046885 - Disable installing webapps in guest mode profiles. r=myk
Bug 881480 - Part 1: Create RDP value forms for ES6 symbols. r=past
Bug 949629 - Reload runtime apps on play. r=paul
Bug 1049744 - Allow panels to expand in WebIDE. r=paul
Merge m-c to fx-team. a=merge
Bug 1057305 - Make mach bootstrap work with elementary os; r=gps

DONTBUILD (NPOTB)

--HG--
extra : amend_source : 40d5633b7099dd0aba9b6933d12aa4d579179694
Merge fx-team to m-c a=merge