Refs #92. Added standard __future__ imports
Refs #92. Moved XmlNamespaceManager to util.xml
Refs #92. Converted test cases to DocumentGenerator test cases
Refs #92. Added a default value of None, set to an empty list
Refs #92. Moved code to the StylesManager
Refs #92. Moved property management to the StylesManager
Refs #92. Refactor to abstract the properties resolution
Refs #92. Fixed the html output ordering
Refs #92. Implemented an iterative style chain resolution algorithm. I don't like the function names, but all tests are passing now.