Rename repr to ent_repr to avoid possible conflicts
Change definition of values for easier parsing
Add dependency and extends definition
Change type of service in Namespace for set() to dict()
Add base class for Service metamodel
Add check to depends parameter

- Check to make sure depends parameter is a list and not None
Add ClassifierBound to model depends/extends/etc. relationship
Implemented basic methods on Service object

- __eq__, __ne__, __hash__ and __repr__ were added, with basic
support.
Refreshing docs

- Fixing spelling errors
- Adding more docstrings