Command inputs, filters, and outputs

[sheenobu]

Build inputs, outputs, and filters that can read/write from the given command.

example: build a command pipeline like tail -f filename | to-json | jq -c | nc 127.0.0.1 8080

{
	"input": {
		"driver":"command",
		"parser": "plain",
                "config": {
                    "command.cmd": "tail -f filename",
                    "command.runforever": true
                }
	},
	"filters": [
		{
			"driver":"command",
			"config": {
				"command.cmd": "to-json",
                                "command.desktination": "message",
			}
		},
		{
			"driver":"command",
			"config": {
				"command.cmd": "jq -c ",
                                "command.merge-keys": ".*",
			}
		}
	],
	"output": {
		"driver":"command"
                "config": {
                    "command.cmd": "nc 127.0.0.1 8080",
                    "command.runforever": true
                }
	}
}