The current OpenShiftCostCategories model stores all the projects (namespaces) in a single array field. This makes is very hard to determine what are default projects and what are user defined.

OpenShiftCostCategories needs to change to only contain name, description and source_type. Currently only the Platform cost category (group) exists and users will be able to add/remove non-default projects from that group.

A new model to hold the namespaces and the many to one relationship between namespace and cost category (group) needs to be created. This model will also store whether or not the namespace is default or user created.