Add examples for creation w/ invalid index; add pending examples for update
Incorporate controller create_task method into tests, modify controller code so tests pass
Begin defining tests for index changes on UPDATE method
Define more tests for indices on update; change controller code to make pass
Define examples for context 'task moved down the list'
Define another example - passes
Define the rest of the 'UPDATE' index tests - passing
Add example for DELETE method
Create final (for now) task indexing tests and make them pass