Added double buffered properties that can be aged

Added double buffered properties that can be aged

There is currently no means of aging a double buffered value on successive updates.
Added a new templated type DoubleBufferedProperty, which holds a double buffered
value type, and can be 'aged' by calling CopyPrevious.

Users of this type (e.g. SceneGraph::Geometry, etc) will call the CopyPrevious method
in the ResetDefaultProperties method (alongside resetting AnimatableProperty values with ResetToBaseValue()).

Removed ownership of scene graph property buffers from Geometry - they are fully
owned by UpdateManager. Instead, Geometry now holds raw pointers to the buffers.

Change-Id: I4682b3f31eb7947fb19ae34871bdc840e9553d5e
Signed-off-by: David Steele <david.steele@partner.samsung.com>