AI 144525: Add structural support for Exchange transport.  The idea is that
  the shipping client will include the necessary generic pieces for
  configuring an Exchange client (e.g. account setup) but will not
  include actual Exchange client code (e.g. transport / protocol).
  Also added a "sample code" implementation of Exchange for use
  as a starting point for implementors.  (Note, this will not ship
  in Donut, it's a placeholder for working on the "framework"
  aspects.)
  BUG=1740621,1740626

Automated import of CL 144525
12 files changed