Bug 1073027 - Control MozLoopService logging with a preference. r=jaws

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extra : rebase_source : 7ba5547518b480c4cab01835662066dab30b5122
Bug 1073047 - Add Firefox Account logging to MozLoopService. r=jaws

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extra : rebase_source : 1010a9157a46a16a28f1befa610716e00da3532a