The current development branch of your project compiles fine for me under MSVC 2013, after I changed the two #include in Connection.cpp from .cpp to .h.
Remember that you need to re-run "cmake ." every time you add a cpp file to the src folder or when you checkout a different git branch, this is because of how we use cmake "in the wrong way" - we don't list the individual source files, but rather use a file globbing mechanism, which unfortunately means that cmake is unable to auto-detect changes when new files are added or removed, and it needs to be run manually after each such change.
Remember that you need to re-run "cmake ." every time you add a cpp file to the src folder or when you checkout a different git branch, this is because of how we use cmake "in the wrong way" - we don't list the individual source files, but rather use a file globbing mechanism, which unfortunately means that cmake is unable to auto-detect changes when new files are added or removed, and it needs to be run manually after each such change.