Bug 785884 - Implement support for temporary storage (aka shared pool). r=ehsan, r=bent

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rename : caps/tests/mochitest/test_principal_extendedorigin_appid_appstatus.html => caps/tests/mochitest/test_principal_jarprefix_origin_appid_appstatus.html
rename : dom/quota/UsageRunnable.h => dom/quota/UsageInfo.h