adding missing readable stream dependency

- although only used for node < 0.10, it still is required in the code
- for node 0.8 it just breaks when trying to find that module

package.json

@@ -8,8 +8,9 @@
     "node": ">= 0.8.0"
   },
   "dependencies": {
+    "bl": "~0.6.0",
     "end-of-stream": "~0.1.3",
-    "bl": "~0.6.0"
+    "readable-stream": "~1.0.26-4"
   },
   "devDependencies": {
     "tap": "~0.4.6",