Use Document.mediatype in to_dict()
Support posting multiple documents in one request
Add utils to change camelcase to underscore and vice versa
Return datetime (created and modified) in isoformat
Add derivedFrom (for modules) in POST /contents request JSON
Merge pull request #12 from Connexions/derive-copy

Derive copy
Merge branch 'master' into multistorage
have testing config use pickle backend