Feature request: Add more information in kapacitor/v1/tasks http end point

__Proposal:__
Expose more information in task info end point (kapacitor/v1/tasks) in order to make incident recovery automation as smooth as possible with record/replay features. Could potentially help more scenarios.

__Current behavior:__
Vital information like every() and period() values are not exposed as key/value pairs, you have to parse them from the script text, unless you have them saved elsewhere per task.

__Desired behavior:__
Expose vital information like every() and period() values as key/value pairs. Every type of value in a task script that controls how and when Kapacitor runs a task should be exposed.

__Use case:__
When automating an incident where Kapacitor has not been able run tasks as a CQ engine for X time, you can back fill (record/replay) aggregated data as long as you still have detailed data for the incident period. In order to automate start/stop time stamps for recordings you need to know for example the values in every() and period() functions. If values like that are exposed in clear key/value pairs a recovery scenario like this will be a lot easier and more straight forward.

Ex. Incident lasts 11 minutes. A CQ task with period(1m), every(1m) will just need start/stop time stamps covering the gap. But a CQ task that has period/every longer than the incident period needs to have a larger window.

Start at the kapacitor/v1/tasks HTTP endpoint and trace how task information is assembled and returned. Determine which task-script values control execution, including every() and period(), and how they should be represented as key/value data. Done means the endpoint exposes the required scheduling information for recovery automation, with coverage for the supported task types.

Written by the indexing model from the issue text.