Bug 897352 - [gaia build system] Transition to a build_stage for assembling apps

Conflicts:
	Makefile
	apps/communications/build/build.js
	build/copy-build-stage-manifest.js
	build/test/integration/distribution.test.js
	build/utils-xpc.js
	build/utils.js
	build/webapp-manifests.js
Bug 963556: Update NFC Manager, Handover to use new shared nfc_utils.js.

Conflicts:
	apps/system/js/nfc_handover_manager.js
	apps/system/js/nfc_manager_utils.js
Merge pull request #17363 from yurenju/stage2

Bug 897352 - [gaia build system] Transition to a build_stage for assembl... r=@ochameau
Merge pull request #17369 from yurenju/nfc

Bug 963556: Update NFC Manager, Handover to use new shared nfc_utils.js. r=@alivedise
Bug 980694 - [B2G][Bluetooth] Bluetooth will continue searching for an export device after it is disabled