Supported API for 3scale CMS - Part 2 - Cleanup

The codebase of the API Manager includes an API for managing the content of the Developer Portal (CMS API). Currently this API is only for internal usage and it is not part of the supported APIs that are available in the solution. This piece is needed for full API lifecycle automation capabilities.

The objective to review the current implementation and perform the necessary work to support the CMS API so it can be used by customers in their production environments.

See this doc for more information.

High level summary of the tasks involved

• Test current implementation and identify weak points or bugs.
• Implement specific improvements or fixes (only if necessary) 
• Enable online documentation for this CMS API in the Admin Portal UI ("3scale API Docs" section in the Admin Portal. Improve the documentation of CMS API.json)
• Allow the creation of Access Tokens with authority to consume the CMS API (new scope in AccountSettings->Personal->Tokens/AddAccessToken)
• Update related documentation in the customer portal. (mansaldo@redhat.com, do you have an issue to link here? mansaldo: we haven't started working on this as of EoDecember 22, due to conflicting priorities)

Out of scope (future enhancements may be requested in separate issues)

• Extending the existing API implementation with new endpoints/features (if needed, docs will include a disclaimer mentioning any particularity or topic not fully covered to take into account in the current implementation).
• Providing new Toolbox CLI commands or other tools to facilitate CMS provisioning tasks. See THREESCALE-8634
• Global versioning for 3scale APIs. See THREESCALE-444
• General API cleanup (json versus XML) for all 3scale APIs. see THREESCALE-5691, THREESCALE-5715, THREESCALE-2137