Cleanup code

This changes variable names that were abbreviations, uses more constants
from the net/http package and improves the json decoding / encoding.

api/api.go

@@ -1,8 +1,11 @@
 package api
 
-import "github.com/gorilla/mux"
+import (
+	"github.com/gorilla/mux"
+	"net/http"
+)
 
-// NewRouter returns an HTTP handler (net.Handler) which can then
+// NewRouter returns an HTTP handler (http.Handler) which can then
 // be used by the net/http package to serve the api of our API.
 // We use gorilla/mux because it is more convenient than net/http,
 // e.g. when extracting path parameters.
@@ -11,7 +14,7 @@ func NewRouter() *mux.Router {
 	// this can later be restricted to a specific host with
 	// `router.Host(...)` and to HTTPS with `router.Schemes("https")`
 	v1 := router.PathPrefix("/api/v1").Subrouter()
-	v1.HandleFunc("/health", Health).Methods("GET")
+	v1.HandleFunc("/health", Health).Methods(http.MethodGet)
 
 	return v1
 }