remove bluebird from deps

.travis.yml

@@ -1,7 +1,5 @@
 language: node_js
 
 node_js:
-  - "0.10"
-  - "0.11"
-  - "0.12"
-  - "iojs"
+  - "4"
+  - "5"

package.json

@@ -1,6 +1,6 @@
 {
   "name": "exeq",
-  "version": "2.2.0",
+  "version": "2.3.0",
   "description": "Excute shell commands in queue",
   "main": "index.js",
   "repository": {
@@ -24,7 +24,6 @@
   },
   "license": "MIT",
   "dependencies": {
-    "bluebird": "^2.6.4",
     "native-or-bluebird": "^1.2.0"
   },
   "devDependencies": {