Create categories for externally added specs

This is the merge request for #95 (closed)

The main idea is that when a new organization is peered then a new category is created with the name of this organization so when the specs are fetched they can be associated with this category. Also this category will be associated with catalog "External Services Catalog". The first time an external organization is peered we create a catalog with name "External Services Catalog", so the following times the catalog is updated with the new category.

The naming convention for both categories & catalogs are up to discussion. Feel free to propose any ideas!