I've created test builds of pgAdmin 4 v2.0-dev and put them at https://developer.pgadmin.org/~dpage/2.0-dev/ for you and any one else that wants them. Windows is missing at the moment - I need to get a new signing cert.
Note that they are completely untested - and I didn't update dependencies before building, so things like OpenSSL and pg_dump etc. might be older versions. Don't worry about that for now - we will update before doing release builds of course.