added initial stub directory and adjusted cmake files to include their tests.
made mock fac/inst/region/market classes to be used with testing. added the stub facility in a new stub namespace and related tests.
updated namespace name to reflect directory name
removed any stubs that aren't facs, regions, insts, or models
added stub inst and region. updated stub facility.
added stub market
added include guards
redisabled facility tests as that
's a larger issue than this PR
encapsulated stubs namespace in cyclus namespace per gcsg