ENH: Enables saving of metadata from the UI.

TODO: Make it more intuitive, ie user should be able to select an existing file.
TODO: ErrorBound will be a spinbox, interpolation method will be a dropdown.
![Screen Shot 2013-03-30 at 6 36 14 PM](https://f.cloud.github.com/assets/1045657/320980/fe4872a6-9981-11e2-8ff2-70bf01c36411.png)