Added fix for instance of Echo that have a prefix (created with Group() method). The URI() method should return prefix plus the calculated string.

Author: newoga

echo.go

@@ -251,7 +251,7 @@ func (e *Echo) URI(h Handler, params ...string) string {
 			}
 		}
 	}
-	return uri.String()
+	return e.prefix + uri.String()
 }
 
 // URL is an alias for URI

echo_test.go

@@ -239,10 +239,16 @@ func TestEchoURL(t *testing.T) {
 	static := func(*Context) {}
 	getUser := func(*Context) {}
 	getFile := func(*Context) {}
+	getGroups := func(*Context) {}
+	getGroup := func(*Context) {}
+
 	e.Get("/static/file", static)
 	e.Get("/users/:id", getUser)
 	e.Get("/users/:uid/files/:fid", getFile)
 
+	eg := e.Group("/groups")
+	eg.Get("/:id", getGroup)
+
 	if e.URL(static) != "/static/file" {
 		t.Error("uri should be /static/file")
 	}
@@ -261,6 +267,18 @@ func TestEchoURL(t *testing.T) {
 	if e.URI(getFile, "1", "1") != "/users/1/files/1" {
 		t.Error("uri should be /users/1/files/1")
 	}
+	if e.URI(getGroups) != "/groups" {
+		t.Error("uri should be /groups")
+	}
+	if e.URI(getGroup, "1") != "/groups/1" {
+		t.Error("uri should be /groups/1")
+	}
+	if eg.URI(getGroups) != "/groups" {
+		t.Error("uri should be /groups")
+	}
+	if eg.URI(getGroup, "1") != "/groups/1" {
+		t.Error("uri should be /groups/1")
+	}
 }
 
 func TestEchoNotFound(t *testing.T) {