Support interactive check boxes in Description

[curran]

Like GitHub

[curran]

Related to #496

If this were done, then you could add checkboxes to the README and it would look like this:

• [X] Task 1
• [ ] Task 2

By writing this code:

 * [X] Task 1
 * [ ] Task 2

Then clicking the checkboxes would edit the text automatically. I think this would be a good approach to adding tasks.

This afforts next level features on top of this, like showing percentage of tasks completed.