CTRL + M + O will collapse all.

CTRL + M + L will expand all. (in VS 2013 - Toggle All outlining)

CTRL + M + P will expand all and disable outlining.

CTRL + M + M will collapse/expand the current section.

CTRL + M + A will collapse all even in Html files.

These options are also in the context menu under Outlining.

Right click in editor -> Outlining to find all options. ( After disabling outlining, use same steps to enable outlining. )

Right-click > Outlining menu