fixes and improvements (#55)

* util/router: sync from github
* config: add watcher interface

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

util/router/compile_test.go

@@ -21,6 +21,13 @@ func TestCompile(t *testing.T) {
 		fields []string
 	}{
 		{},
+		{
+			segs: []segment{
+				literal(eof),
+			},
+			ops:  []int{int(OpLitPush), 0},
+			pool: []string{""},
+		},
 		{
 			segs: []segment{
 				wildcard{},