Adding a failing test for folder-level metadata.
Adding folder-level metadata.
Using more modern dictionary initialization.
Merge pull request #331 from girder/folder-metadata-server

Folder metadata server
When a file is partially uploaded, and file/complete is called, don't allow the file to be finished.  Doing so results in a file whose metadata length differs from its actual length.  I've added a check that if the upload 'behavior' is set, to not use this check, as that currently breaks S3 uploads.
Merge branch 'dont-complete-partial-files' of https://github.com/manthey/girder into dont-complete-partial-files