Local beta files for refactorying the file-tree code

- Want to separate weblearn-specific functionality from file-tree, so that
  file-tree.js can be as general as possible (maybe even integrated onto
  the original's on github)
Refactor fileTree input parameters into the options literal
Remove weblearn-specific methods and make options slightly clearer
Rename options to settings
Save selectors for efficiency (so dom doesn't repeatedly need traversing)
Remove test file
Refactor file-tree and folder-listing code

- Weblearn-specific code has been moved into folder-listing wrapper
Fix dialog to use refactored folder-listing code