Visual candy for the "Save as" GUI 

Introduces various widgets for controlling the output file.

The options currently available are based on the documentation for GDAL 1.10 and will need to be adjusted if changes are made on GDAL side.
![screenshot from 2013-11-21 13 49 59](https://f.cloud.github.com/assets/588407/1591705/7afa426a-52ab-11e3-83a1-8319b5d75b98.png)