Removed logging dependencies.

This commit removes the logging framework included in `btcscript`. It has the side-effect of working with the App Engine runtime.

See https://github.com/conformal/btcscript/issues/16 for more discussion on why logging in `btcscript` might not be appropriate/needed.

Note that these changes will affect packages that use the logging API of `btcscript` as the API has been removed.