robo(1): add --quiet option

The option renders the task names only, allows users to implement scripting
easily with robo.

Closes #46.

main.go

@@ -12,7 +12,7 @@ var version = "0.6.0"
 
 const usage = `
  Usage:
- robo [--config file]
+ robo [-q] [--config file]
  robo <task> [<arg>...] [--config file]
  robo help [<task>] [--config file]
  robo variables [--config file]
@@ -23,6 +23,7 @@ const usage = `
  -c, --config file config file to load [default: robo.yml]
  -h, --help output help information
  -v, --version output version
+ -q, --quiet output task names only
 
  Examples:
 
@@ -62,6 +63,11 @@ func main() {
  default:
  if name, ok := args["<task>"].(string); ok {
  cli.Run(c, name, args["<arg>"].([]string))
+ return
+ }
+
+ if args["--quiet"].(bool) {
+ cli.ListNames(c)
  } else {
  cli.List(c)
  }