'createSubscribeQuery' only works when share is connected under WebSockets

I'm pretty sure this is because "socket.canSendWhileConnecting" is not set- but _createQuery will silently fail in WebSockets like this:

``` js
var proto = 'ws'
var collection = 'files'
var socket = new WebSocket(proto + '://' + location.hostname + ':' + location.port)
var sharejs = require('share/lib/client/index')
var share = new sharejs.Connection(socket)

var query = share.createSubscribeQuery(collection, {}, {docMode:'sub'}, function(err, documents) {
console.log('not called')
})
```

while this will work as expected:

``` js
var proto = 'ws'
var collection = 'files'
var socket = new WebSocket(proto + '://' + location.hostname + ':' + location.port)
var sharejs = require('share/lib/client/index')
var share = new sharejs.Connection(socket)

share.on('connected', function() {
var query = share.createSubscribeQuery(collection, {}, {docMode:'sub'}, function(err, documents) {
console.log('called')
})
})
```

So, for WebSockets/BCSockets consistency the above should probably throw an error when canSendWhileConnecting is false.