JSON

- Corrected misleading comment.
Unit Tests

- Removed backslash.t, which duplicates tests in bug.879.t.
Unit Tests

- Removed excessive tests that add nothing.
Unit Tests

- Removed unnecessary backslashes in the unit test.  It was confusing and
  testing the wrong thing.
Unit Tests

- Not enough backslashes in the unit test, and taskwarrior will need to add
  an extra decode on Task::set and Task::addAnnotaiton.
Task

- Now decodes backslashes on attribute set.
Task

- Now decodes backslashes on annotation add.