[COOK-4224] Use an array to define Time Period times

Currently a comma delimited string is used to define "times" for a timeperiod. However, commas are valid characters for the definitions themselves.

For example, the following is valid a Nagios timeperiod definition, but it is not possible to define with current cookbook because the commas would be used to split the string:

```
define timeperiod { 
  timeperiod_name primetime 
  alias When things are normal 
  sunday 00:00-06:00,12:00-24:00
  monday 00:00-06:00,12:00-24:00
  tuesday 00:00-06:00,12:00-24:00
  wednesday 00:00-06:00,12:00-24:00
  thursday 00:00-06:00,12:00-24:00
  friday 00:00-06:00,12:00-24:00
  saturday 00:00-06:00,12:00-24:00 
}
```
Using an array to define the "times" inside the nagios_timeperiods data bag will solve this issue.

I updated the README example, but here it is so you can see the array:

```javascript
{
  "id": "time_period_name",
  "alias": "This time period goes from now to then",
  "times": [
    "sunday 09:00-17:00",
    "monday 09:00-17:00",
    "tuesday 09:00-17:00",
    "wednesday 09:00-17:00",
    "thursday 09:00-17:00",
    "friday 09:00-17:00",
    "saturday 09:00-17:00"
  ]
}
```