migrate to upstream libcompose in one and a half go

vendor/github.com/gorilla/context/.travis.yml

@@ -4,6 +4,4 @@ go:
   - 1.0
   - 1.1
   - 1.2
-  - 1.3
-  - 1.4
   - tip

vendor/github.com/gorilla/context/context_test.go

@@ -98,7 +98,7 @@ func parallelReader(r *http.Request, key string, iterations int, wait, done chan
 func parallelWriter(r *http.Request, key, value string, iterations int, wait, done chan struct{}) {
 	<-wait
 	for i := 0; i < iterations; i++ {
-		Set(r, key, value)
+		Get(r, key)
 	}
 	done <- struct{}{}