Browserify cqs dynamically in ddoc.js

Currently, I'm getting this error:

```js
> require('./').defaults({couch:'http://127.0.0.1:5984/',db:'cqs_queue',browser_attachments:!0}).CreateQueue('t',console.log)
TypeError: Object #<Object> has no method 'add_browser'
    at Transaction.add_queue (cqs/queue.js:147:12)
    at run_op (cqs/node_modules/txn/lib/txn.js:258:10)
    at cqs/node_modules/txn/lib/txn.js:229:14
    at cqs/node_modules/txn/lib/lib.js:68:12
    at Request._callback (cqs/node_modules/txn/lib/lib.js:125:12)
    at Request.self.callback (cqs/node_modules/request/index.js:142:22)
    at Request.EventEmitter.emit (events.js:98:17)
    at Request.<anonymous> (cqs/node_modules/request/index.js:856:14)
    at Request.EventEmitter.emit (events.js:117:20)
    at IncomingMessage.<anonymous> (cqs/node_modules/request/index.js:808:12)
```

I'll merge this PR as soon as I get it working.