Removed unused helper optional_parameter

Was used to mark an optional paramter, now being done with attribute in
YAML
Endpoint examples now list examples by language.

As a pre-cursor to adding examples for ruby and php clients in addition
to curl.
Fix missing curl example for user endpoint
Remove the arbitrary printing of endpoint response.

Can now stop deleting properties from the yaml data, which was
persisting across page loads.
Examples partial for showing examples in endpoints.
Cleanup unused code; remove default when endpoint is missing response.

All endpoints have (and should have) response specified.