etcd: Rewrite embed etcd implementation

This is a giant cleanup of the etcd code. The earlier version was
written when I was less experienced with golang.

This is still not perfect, and does contain some races, but at least
it's a decent base to start from. The automatic elastic clustering
should be considered an experimental feature. If you need a more
battle-tested cluster, then you should manage etcd manually and point
mgmt at your existing cluster.

main.go

@@ -27,7 +27,6 @@ import (
 // These constants are some global variables that are used throughout the code.
 const (
 	Debug   = false // add additional log messages
-	Trace   = false // add execution flow log messages
 	Verbose = false // add extra log message output
 )
 
@@ -40,7 +39,6 @@ var (
 func main() {
 	flags := mgmt.Flags{
 		Debug:   Debug,
-		Trace:   Trace,
 		Verbose: Verbose,
 	}
 	if err := mgmt.CLI(program, version, flags); err != nil {