Merge pull request #26 from pysailor/master

Make the uploader work in an Archetypes-free site
Handle HTTP status code 500 explicitly.

This makes quickupload display the serverError message in case the
request dies with HTTP status code 500.
Merge pull request #27 from durko/master

Handle HTTP status code 500
Update HISTORY.txt
re-engineered _listTypesForInterface to work both with AT and dexterity. Simplified UploadFileTypeVocabulary,
since it now relies on _listTypesForInterface to make the distinction.
Lastly, some flake8 for good measure