Unit Tests - Config

- Added unit tests for Config.  Why didn't I do this a year ago?
- Shut off old 1.7.0 code (gulp).
- Task now thoroughly broken, and only 1.8.0 can help.

src/Config.cpp

@@ -270,7 +270,7 @@ const std::string Config::get (
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-bool Config::get (const std::string& key, bool default_value)
+bool Config::get (const std::string& key, const bool default_value)
 {
   if ((*this).find (key) != (*this).end ())
   {