Removed Boost as a dependency from Expected, so Expected can now function standalone with a very minimal boost macros header file

In the process tidied up quite a bit of historical cruft. Verified as compiling and passing all unit tests on GCC 4.8 and VS2013.

If you can let me remove Boost.Move support, I can simplify things still further e.g. strip out BOOST_FWD_REF et al.