Remove out of date comment

Decided not to reset the default on the basis that it may change again,
and people will be best served by referring to the config for the
default.
Disable compress.zlib on GAE

Currently unsupported.
Check for presence of val in data array

In model. I think this simpler patch should accomplish the same as
issue 44.
Merge pull request #54 from ianbarber/master

Small tidy ups