internal/config: refactor option parsing

- authorize: build whitelist from policy's URLs instead of strings.
- internal/httputil: merged httputil and https package.
- internal/config: merged config and policy packages.
- internal/metrics: removed unused measure struct.
- proxy/clients: refactor Addr fields to be urls.
- proxy: remove unused extend deadline function.
- proxy: use handler middleware for reverse proxy leg.
- proxy: change the way websocket requests are made (route based).

General improvements
- omitted value from range in several cases where for loop could be simplified.
- added error checking to many tests.
- standardize url parsing.
- remove unnecessary return statements.

- proxy: add self-signed certificate support. #179
- proxy: add skip tls certificate verification. #179
- proxy: Refactor websocket support to be route based. #204

internal/metrics/exporter.go

@@ -18,8 +18,7 @@ func newPromHTTPHandler() http.Handler {
 	// TODO this is a cheap way to get thorough go process
 	// stats.  It will not work with additional exporters.
 	// It should turn into an FR to the OC framework
-	var reg *prom.Registry
-	reg = prom.DefaultRegisterer.(*prom.Registry)
+	reg := prom.DefaultRegisterer.(*prom.Registry)
 	pe, _ := ocProm.NewExporter(ocProm.Options{
 		Namespace: "pomerium",
 		Registry:  reg,