Updated 'flex-sdk' dep to fix Mavericks build. Targeting Flash 11.0.0.

Updated 'flex-sdk' dep to fix Mavericks build.  Fixes #259.

Also now targeting Flash 11.0.0, which enables us to make necessary changes for #373.


@jonrohan: You may need to do the following to get it working locally:

```shell
npm cache clean flex-sdk
npm cache clean grunt-mxmlc
npm install
```