Move to v2 module and enable stream redirection

[alexellis]

Description

Move to v2 module and enable stream redirection

• Moves to v2 module style as per google/github-go
• Allows stdio buffer to be disabled for large outputs
• Allows stdio reader/writer replacement fixes: Allow intercepting the stdout/stderr for processing #12
• Closes: fix: do not assume bash lives in /bin #13

How Has This Been Tested?

package main

import (
	"bytes"
	"context"
	"fmt"

	gexec "github.com/alexellis/go-execute/v2"
)

func main() {
	buf := bytes.NewBuffer(nil)

	t := gexec.ExecTask{
		Command:            "whoami",
		Shell:              true,
		StreamStdio:        false,
		StdOutWriter:       buf,
		DisableStdioBuffer: true,
	}

	r, err := t.Execute(context.Background())
	if err != nil {
		panic(err)
	}

	if r.ExitCode != 0 {
		panic(r.Stderr)
	}

	fmt.Printf("r.Stdout: %q\n", r.Stdout)
	fmt.Printf("Buffer: %q\n", buf.String())
}

Output:

go run .
r.Stdout: "alex\n"
Buffer: "alex\n"

Also tested with shell enabled/disabled, and with StreamStdio enabled.

Checklist:

I have:

• updated the documentation and/or roadmap (if required)

[alexellis]

@michaeladler @josegonzalez

[michaeladler]

LGTM