Bug 963639 - only make Australis customization mode set customizing=true on toolbars which are customizable, r=MattN

--HG--
extra : rebase_source : 3aaf5c0ab1188c15acddf5187f786ee32b1af677
Bug 968316 - Keep the highlighter visible when selecting the currently hovered node in the markup-view, r=bgrins
Bug 965196 - [OS.File] Add an option |backupTo| to writeAtomic. r=Yoric
Bug 967907 - Change the SUMO URL for Metro Firefox [r=jimm]
Bug 963046 - Add Picasso image loading library to the tree (r=nalexander)
Bug 963046 - Use HomeItems DB constract in PanelListRow (r=margaret)
Bug 963046 - Add image_url column to HomeProvider's fake items (r=margaret)
Bug 963046 - Use Picasso to load images in PanelListRow and PanelGridItemView (r=margaret)
Bug 963046 - Remove unused imports from PanelListRow (r=margaret)
Merge m-c to fx-team.
bug 963505 - iframes should load with low network priority r=bz

--HG--
extra : rebase_source : af21eb1a58111b7ee204a2b8e16a935f8dacbfce
Backed out changeset ed28aeea074a (bug 964511) r=margaret
Backed out changeset 2c2c426e4afe (bug 784759) r=margaret
Backed out changeset b8c9dc39af31 (bug 964510) r=margaret
Backed out changeset 60651784715f (bug 967254) r=margaret
Backed out changeset 71118c075821 (bug 947550) r=margaret on a CLOSED TREE
Bug 969169 - ensure logging is only initialized once. r=ttaubert
Bug 850721 - fix social blocklist oranges by not enabling the default update server. r=mixedpuppy
Bug 966241, revert some of bug 941051 and just use Intersect instead of IntersectRect, r=neil
Bug 943339 - Part 1: Only store a subset of session history entries to file. r=Yoric