removing khan-exercises
Squashed 'kalite/static/js/khan-exercises/' content from commit e550618

git-subtree-dir: kalite/static/js/khan-exercises
git-subtree-split: e550618b86d22cf5eb3738e46b6be358a0e7f014
Merge commit 'b927bd58ae409e78358e4b56fdbd4986a3e78b68' as 'kalite/static/js/khan-exercises'
short-term hack to fix #1607
Merge pull request #1585 from bcipolli/1584

Fix #1584 (Spanish khan-exercises) by adding khan-exercises as a subtree