- Add support for single channel defined as a string rather than an array (removes the need of having 2 different handlers)
- Implement a retry strategy for handling slack api transitient errors (like timeouts). Retries hardcoded to 5 with 10 second timeout, but we should make this a setting
- Exits with non zero status on api call errors, to allow sensu-server to catch the output and log it
- Deals with non-nagios standard exit codes for checks (0-3), also known as "out of bounds" errors
	- Sets the color the same as UNKNOWN
	- Displays the exit code as it was returned by the check, for detailed information

Keep client and check names in the title

Co-Authored-By: kali-brandwatch <[email protected]>

Change to string interpolation

Co-Authored-By: kali-brandwatch <[email protected]>

Change to string interpolation

Co-Authored-By: kali-brandwatch <[email protected]>

Change to string interpolation

Co-Authored-By: kali-brandwatch <[email protected]>

- Remove unnecessary puts for the whole request.
- Fix syntax error on string interpolation.
- Shorten error messages to keep clearer error messages and make rubocop happy about line length.

…dard exit codes

As discussed on sensu-plugins#82 (comment) and sensu-plugins#82 (comment)
Add a configurable setting for which exit status code will be used when the check returns a non standard status (non [0..3]), defaulting to 3 (UNK)
Set rescues on `color` and `translate_status` to use this setting.
Should resolve both comments above