Bug 1094272 - Use a single process.

The child process has sometimes thrown exceptions and crashed,
but the main process continues to consume messages and write
them to the shared queue, thus losing them.  There's no real
need to have multiple processes; instead, we should use the
fact that messages will be queued in RabbitMQ if
pulsetranslator gets stuck on one for a while.

In addition,
* fix an exception when platform field is None
* add usage instructions to README
* clean up miscellaneous bits
The disadvantage here of not using any kind of queue, I realized, is that we can block for up to 10 minutes while waiting for a log to appear, during which we won't consume any new messages, and they'll build up on the server, likely triggering nagios alerts.  If there are any logurl's in the pulse stream which are just plain wrong, this will likely have the effect of making us fall permanently behind.  I guess we can land this and see if this problem actually happens...it's theoretical at this point.