replace imports of q with bluebird

update `package.json`

```
find src test -name '*.js' |
   xargs perl -i -pe 'if (/require\(.[qQ].\)/) { $_ = "import Promise from '\''bluebird'\'';\n"; }'

find src test -name '*.js' |
   xargs perl -i -pe 'if (/import [qQ]/) { $_ = "import Promise from '\''bluebird'\'';\n"; }'
```

package.json

@@ -46,6 +46,7 @@
   },
   "dependencies": {
     "babel-runtime": "^6.11.6",
+    "bluebird": "^3.5.0",
     "blueimp-canvas-to-blob": "^3.5.0",
     "browser-encrypt-attachment": "^0.3.0",
     "browser-request": "^0.3.3",
@@ -68,7 +69,6 @@
     "matrix-js-sdk": "matrix-org/matrix-js-sdk#develop",
     "optimist": "^0.6.1",
     "prop-types": "^15.5.8",
-    "q": "^1.4.1",
     "react": "^15.4.0",
     "react-addons-css-transition-group": "15.3.2",
     "react-dom": "^15.4.0",