Download button

I've added a setting to show a download button (http://support.jwplayer.com/customer/portal/articles/1436999-example-adding-a-download-button).
![bildschirmfoto 2014-12-09 um 12 11 44](https://cloud.githubusercontent.com/assets/4180675/5356420/a349bf7e-7f9c-11e4-9137-53123569cae3.png)
![bildschirmfoto 2014-12-09 um 12 12 03](https://cloud.githubusercontent.com/assets/4180675/5356421/a34a80a8-7f9c-11e4-9bcc-154483989065.png)
![bildschirmfoto 2014-12-09 um 12 11 54](https://cloud.githubusercontent.com/assets/4180675/5356422/a34aec0a-7f9c-11e4-84ce-885782534921.png)