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"; }'
```

test/app-tests/joining.js

@@ -33,7 +33,7 @@ var React = require('react');
 var ReactDOM = require('react-dom');
 var ReactTestUtils = require('react-addons-test-utils');
 var expect = require('expect');
-var q = require('q');
+import Promise from 'bluebird';
 
 var test_utils = require('../test-utils');
 var MockHttpBackend = require('matrix-mock-request');

test/app-tests/loading.js

@@ -22,7 +22,7 @@ import React from 'react';
 import ReactDOM from 'react-dom';
 import ReactTestUtils from 'react-addons-test-utils';
 import expect from 'expect';
-import q from 'q';
+import Promise from 'bluebird';
 
 import jssdk from 'matrix-js-sdk';
 

test/test-utils.js

@@ -1,6 +1,6 @@
 "use strict";
 
-var q = require('q');
+import Promise from 'bluebird';
 
 /**
  * Perform common actions before each test case, e.g. printing the test case