Refs #71. Added __future__ imports to the top of the module
Refs #71. Added basic Styles parsing with test cases
Refs #71. Handle processing rPr as RunProperties
Refs #71. Add a facility for fetching styles by type
Refs #71. Added more test cases
Refs #71. Pulled the logic of parsing tags and attributes out into an abstracted XmlModel class
Refs #71. Updated test cases
Refs #71. Moved xml model parsing abstraction to a different location
Refs #71. Moved styles to models