Remove BufferedSink

Author: clue

composer.json

@@ -9,12 +9,10 @@
     },
     "require-dev": {
         "react/event-loop": "^0.4|^0.3",
-        "react/promise": "^2.0|^1.0",
         "clue/stream-filter": "~1.2"
     },
     "suggest": {
-        "react/event-loop": "^0.4",
-        "react/promise": "^2.0"
+        "react/event-loop": "^0.4"
     },
     "autoload": {
         "psr-4": {