Updated to Image Pack import process...

Did not fundamentally change the actual import, but the UI and user feedback for imports.  As a new user, I tried to import some bad packs (I'd downloaded them incorrectly).  So on each one, I would get an error message followed by the generic "Images imported successfully" message which created confusion for me.

As an initial test of shared development, I decided to clean this up.  Hope you approve.

Now at the end of the import, it gives you a list of the successful packs and a list of the unsuccessful ones and why.

![image](https://f.cloud.github.com/assets/814669/660693/6e746a10-d70f-11e2-9e97-ded4956677d7.png)