Provide HTML documentation

- Added ViewModel -> HTML ContentNegotiation mapping
- Configured template_path_stack for current module
- Set template name in controller, for those renderers that might use templates
- Basic Bootstrap-based views for listing APIs, and then all services in an API

TODO:

- Page for individual service in an API
- Reduce some code duplication if possible
Merge branch 'feature/html-docs'

Provide HTML documentation using basic Bootstrap interactions.