Remove namespace, utcseconds, add msg header, rename purge -> flush

1) Neither namespace or utcseconds are *really* needed, and removing
them simplifies the scripts and increases performance substantially.
If time is needed in the client, it can be added to the message in
whatever format required. For now we should be trying to do the least
possible and build additional features on top of the foundation.

2) Add a header to each message to prevent duplicates from being lost
in the sorted sets and allow messages to be traced along routes.
This adds a bit more storage requirements, but is worth it.

3) "Flush" makes more sense than "purge". Otherwise unchanged.
Add version file, set version at 0.0.2

It'll be important to track and version the API of the lua scripts.
0.0.2 seems like the right version to start at since we're still
really early in development and we've just broken compatibility
with the previous version.