[Bugfix] Idempotency when trying to create a service twice

It was implemented everything for this feature but the error handler when
CAPI V3 answered with a 422 status code with the message
the service instance name is taken.

api/cloudcontroller/ccv3/errors.go

@@ -171,6 +171,9 @@ func handleUnprocessableEntity(errorResponse ccerror.V3Error) error {
 	case strings.Contains(errorString,
 		"Assign a droplet before starting this app."):
 		return ccerror.InvalidStartError{}
+	case strings.Contains(errorString,
+		"The service instance name is taken"):
+		return ccerror.ServiceInstanceNameTakenError{Message: err.Message}
 	case orgNameTakenRegexp.MatchString(errorString):
 		return ccerror.OrganizationNameTakenError{UnprocessableEntityError: err}
 	case roleExistsRegexp.MatchString(errorString):

api/cloudcontroller/ccv3/errors_test.go

@@ -486,6 +486,27 @@ var _ = Describe("Error Wrapper", func() {
 						})
 					})
 
+					When("the service instance name is taken", func() {
+						BeforeEach(func() {
+							serverResponse = `
+{
+  "errors": [
+    {
+      "code": 10008,
+      "detail": "The service instance name is taken",
+      "title": "CF-UnprocessableEntity"
+    }
+  ]
+}`
+						})
+
+						It("returns an ServiceInstanceNameTakenError", func() {
+							Expect(makeError).To(MatchError(ccerror.ServiceInstanceNameTakenError{
+								Message: "The service instance name is taken",
+							}))
+						})
+					})
+
 					When("the buildpack is invalid", func() {
 						BeforeEach(func() {
 							serverResponse = `