Bug 828654 - pre: Make BagheeraRequestDelegate callbacks include namespace and id.

This is convenient for my use of the Bagheera client, and prepares us
for having the server generate ids.
Bug 828654 - pre: Add HealthReportStorage.hasEventSince.
Bug 828654 - pre: Move uses-permission into correct manifest snippet.
Bug 828654 - Part 1: Factor reflecting-to-Fennec code into BackgroundService.

This also renames the label of the method reflected to Fennec in
anticipation of additional methods.
Bug 828654 - Part 2: Add Health Report permissions and services manifest fragments.

Also adds used to broadcast pref from Fennec to background services.
Bug 828654 - Part 3: Health Report Upload service start/stop/schedule boilerplate.
Bug 828654 - Part 4: Implement HealthReportUploadPolicy.
Bug 828654 - Part 5: Implement AndroidHealthReportUploadClient.
Bug 840127 - Delete obsolete documents when health report uploading is turned off.