Make the DefaultHttpPattern more configurable

[pointlander]

The DefaultHttpPattern needs more configuration options such as circuit breaker options. The pattern can be found here: https://github.com/project-flogo/microgateway/blob/master/internal/pattern/DefaultHttpPattern.json After changing this file the assets need to be generated with 'go generate' in the pattern directory. After adding more configuration options this code needs to be updated to use them:
https://github.com/project-flogo/microgateway/tree/master/examples/api/default-http-pattern
and
https://github.com/project-flogo/microgateway/tree/master/examples/json/default-http-pattern