Right-click on file name to show in explorer

Added a context menu action to the file combo/action bar in order to view the current file in the project explorer.
![screenshot from 2014-03-22 17 09 09](https://f.cloud.github.com/assets/2462770/2490976/fde83b46-b1d3-11e3-9c53-97de77a792cd.png)