Add support for Function and Trigger domain objects (#1060)

Vast commit, includes:

 * Introduces the Trigger domain entity.
 * Introduces the Fns domain entity.
 * V2 of the API for interacting with the new entities in swaggerv2.yml
 * Adds v2 end points for Apps to support PUT updates.
 * Rewrites the datastore level tests into a new pattern.
 * V2 routes use entity ID over name as the path parameter.

test/fn-system-tests/exec_test.go

@@ -331,7 +331,7 @@ func callFN(ctx context.Context, u string, content io.Reader, output io.Writer,
 }
 
 func getAPIURL() (string, *url.URL) {
-	apiURL := getEnv("FN_API_URL", "http://localhost:8080")
+	apiURL := getEnv("FN_API_URL", "http://localhost:8085")
 	u, err := url.Parse(apiURL)
 	if err != nil {
 		log.Fatalf("Couldn't parse API URL: %s error: %s", apiURL, err)

test/fn-system-tests/system_test.go

@@ -34,10 +34,6 @@ const (
 	LBAddress = "http://127.0.0.1:8081"
 )
 
-type SystemTestNodePool struct {
-	runners []pool.Runner
-}
-
 func LB() (string, error) {
 	u, err := url.Parse(LBAddress)
 	if err != nil {