If the spacex grpc modules are not available in the import path, will now fall back to using reflection to get them dynamically. I'm not real happy with the mess this made of the import lines, though (and neither is pylint...), so I may hack on that a little further when I get the time.
Add a requirements.txt file to enable installation of all prerequisites so users don't have to follow the individual instructions for each dependency package. At some point, I'll really need to add proper Python packaging so the whole thing can just be installed via pip.
Rearrange the README a bit, since some of the sections have increased or decreased in relevance over time.
