Submit to multiple problems at once

For some assignments, there are many parts to a single question but each file must be submitted on its own. 

This feature will automatically submit files to matching problems.

![marmoset screenie](https://cloud.githubusercontent.com/assets/1113218/4265626/238c0eae-3c58-11e4-9c76-d5658b2e67a8.png)

Good point about the zip. My first assignment only required txt files but the default list should probably be added to.