Merge branch 'mapping_caps'

Merge branch 'mapping_caps'

Closes T187.

This merge implements mapping capabilities that replace the need for
creating copies of Frame capabilitites when mapping the same Frame
capability multiple times.  Mapping capabilities are derived from
the type that is mapped (e.g.  Frame_Mapping for Frame capabilities)
and are created in a provided, free capability slot on a VNode map
invocation.  Further the VNode unmap invocation now takes a VNode
and a Mapping capability as it's arguments.

Further changes in this merge are:
 * 64 byte capabilities on all supported architectures and platforms
 * The address property of a capability can be defined recursively

Signed-off-by: Simon Gerber <simon.gerber@inf.ethz.ch>