Filter outgoing HttpRequests

[xordi]

Currently, all outgoing requests through HttpClient are counted and summarized. We should provide a way to specify a configuration for a given base address that must include:

• A set of paths to take into account in metrics. If none is specified, take into account all paths for the specified base address.
• When a path is defined, we can decide if show just the defined path value or show all the actual requested path. For example:
  Let's assume we define a path which is /A/B. If we decide to show all the requested path, if a request is made to /A/B/C, then metrics should be counted on /A/B/C. If we decide not to show al the requested path, if a request is made to /A/B/C, we will count it on /A/B.
• Whether to include or not the query string parameters in the metrics.