tests for UUID
Move the UUID handling to the batch

The reasoning being that a batch is the uniq data set that will be
transported.
Retry EOF errors when posting

I believe this is happening because of a race condition wrt TLS sessions
being closed right before a POST. See also:
https://code.google.com/p/go/issues/detail?id=3514

Moved the Drop/Lost/UUID stuff to the batch for retry purposes.
Log final EOF error
s/MaxRetries/MaxAttempts/ as that's what it really is atm
Bump version to 0.7.0