Require php-stream-filter 1.4

This will avoid some bugs in 1.3. This will fix #78

Author: Nyholm

composer.json

@@ -14,7 +14,7 @@
         "php": ">=5.4",
         "psr/http-message": "^1.0",
         "php-http/message-factory": "^1.0.2",
-        "clue/stream-filter": "^1.3"
+        "clue/stream-filter": "^1.4"
     },
     "provide": {
         "php-http/message-factory-implementation": "1.0"