Add todo uncomplete event and track upon uncompletion
README update
Refactor some methods in household 

with respect to change to using state machine in Completable
Fix bug in Completable#uncomplete callback
code style fix
todos are dependent destroy on its household
Move off the html version of household show
REFACTOR: Use 1 collection instead of 2 in the backbone app

Previously we were using separate collections 
for the active todos and the completed todo lists.
Now we just have a single collection and each list
view filters the appropriate todos.