Add configurations to the solution file to build czmq DLLs
 * Adds two new configurations in the Solution: DebugDLL and ReleaseDLL
 * czmq_selftest does not build when the DLL config is selected because
   the *_test() functions aren't exported by the DLL, so the build would
   fail
Merge pull request #128 from vortechs2000/BuildsWindowsDLLs

Add configurations to the solution file to build czmq DLLs for Windows builds