Added the ability to exclude current tokens from the autocomplete 

I've added two options to allow for the exclusion of current tokens from the autocomplete dropdown.

As you can see Javascript doesn't show up again in the screenshots below.
![one](https://f.cloud.github.com/assets/595547/2415064/e0ac3a12-aaf0-11e3-8088-0bca07ea1271.png)
![two](https://f.cloud.github.com/assets/595547/2415066/e213b0b0-aaf0-11e3-93e6-f58c6fed2df7.png)

The params are:
`
excludeCurrent: bool
excludeCurrentParam: string The query string param to send back to the server
`