Impossible to reload task with kapacitor cli

Sometimes, tasks are not visible on the `kapacitor list tasks` command but they are visible through api.

Also kapacitor first runs GET command, then he fetches this "unexisting task", and then runs the PATCH http command, which doesn't update properly this unexisting task.

If task is not visible in the `kapacitor lists tasks` command, then it should be visible though api also.

As a result of all this it is not possible to cleanly delete and define tasks, rather, they are always updated, which also doesn't work as mentioned in #941

Start by reproducing the mismatch between `kapacitor list tasks` and the task API, then trace the CLI's GET and PATCH requests for a task that is not listed. Compare the task lookup and update paths, and consider the issue complete when tasks can be cleanly listed, deleted, and defined without an incorrect update of a nonexistent task.

Written by the indexing model from the issue text.