Download All Files Recursively & Results Path Fix

Implemented a new method which now recursively downloads all files in a student's repo when the "Download all files" button is pressed in the Repo Browser. Before only files in the current directory were downloaded and sub-directories were disregarded. 

The path variable for files in the Results page is now correct and files are displayed.
Prefer single-quoted strings when you don't need string interpolation or special symbols.