Bug 1059391 - Add pref to disable caching of Sync authentication credentials. r=markh

This introduces a debugging pref, "services.sync.debug.ignoreCachedAuthCredentials".
This flag allows testers to disable caching of authentication credentials
to make debugging of expired and revoked credentials easier. This will
help expedite any visble auth errors resulting from a expired or revoked
FxA session token, e.g., from resetting or changing the FxA password.
This pref is not set by default.
Bug 1031273 - "Clear Private Data" does not clear "Recently closed tabs" from Recent Tabs. r=margaret
Bug 1057685 - regression: Tweak Browser:Quit to maintain existing support for add-ons - part deux, r=wesj
Bug 1058133: Telemetry for tracking protection events (r=bmcbride)
Bug 1048882 - The warning displayed when closing window (feedback_window_will_close_in) needs a plural form. r=standard8

--HG--
extra : rebase_source : 754995dddbcad6777e7b9def30f20fe3e3744bfc
Bug 977267 - [a11y] Make autocomplete suggestions accessible to screen readers. r=bgrins
Bug 1055333 - Skip browser_styleeditor_cmd_edit.js in e10s. r=harth
merge fx-team to mozilla-central a=merge