Added module: command-dispatcher, allows shell commands to be run

[SimonThalvorsen]

Ticket: CFE-4627

[larsewi]

Please check (if you have not already) how the README.md of other modules are written and try to make it consistent. You can use this module as a template https://github.com/cfengine/modules/blob/master/promise-types/git/README.md

[larsewi]

Suggested change

	Internally these commands are ran using the `"useshell"`-promise based
	on the `condition`-variable.
	Internally these commands are ran using the `"useshell"`-promise based on the `condition`-variable.

[larsewi]

Suggested change

	`condition` - Condition for running e.g `linux`, `debian`, etc. Defaults to `"any"`
	`condition` - Condition for running. Use a class expression (e.g., `linux|bsd`). Defaults to `"any"`

[larsewi]

Suggested change

	`ifelapsed` - Number of minutes between assessments. Defaults to 5
	`ifelapsed` - Number of minutes between assessments. Defaults to 5 minutes.

[larsewi]

Suggested change

	```
	...
	{
	"command": "echo \"Hello World\"",
	"condition": "linux",
	"ifelapsed": "5"
	},
	...
	```
	```json
	...
	{
	"command": "echo \"Hello World\"",
	"condition": "linux",
	"ifelapsed": "5"
	},
	...

[larsewi]

Suggested change

	Would echo "Hello world" on every linux devices in 5 minute intervals.
	Would echo "Hello world" on every linux devices in 5 minute intervals.

[larsewi]

Also read this https://github.com/cfengine/build-index/blob/master/CONTRIBUTING.md