feat: remove qs dependency

Author: yugasun

package.json

@@ -32,8 +32,7 @@
     "vue": "^2.5.2"
   },
   "dependencies": {
-    "axios": "^0.17.1",
-    "qs": "^6.5.1"
+    "axios": "^0.17.1"
   },
   "devDependencies": {
     "babel-core": "^6.26.0",