Document: Refactor behaviors to be a package with separate modules.
Cleanup: Docstrings, spelling.
Add assertion to existing test that didn't have one.
Extract document metadata into separate behavior.
Re-add previously removed FileOrPaperValidator.
Merge pull request #278 from 4teamwork/lg-extract-document-metadata-into-behavior

Extract document metadata into separate behavior
Pass filename as title attribute to content constructor.
Add missing test cases: Test if there's only one journal entry with the filename in the action title.
No longer fire ObjectAddedEvent a second time. createContentInContainer does this already.
Make sure the named_file is already set when the ObjectAdded event gets fired.
Replace mock test cases by functional tests.