refactor(commands): separate commands and its core into two folders (#32)

- I think it would be better if one for commands only, one for the spec
handling core logic so people won't be confused by the core logic inside
the commands folder (cleaner I guess)
- Regen docs

commands/sys/launchctl.go

@@ -1,14 +1,14 @@
 package sys
 
 import (
-	"github.com/versenilvis/iris/commands/core"
+	"github.com/versenilvis/iris/spec"
 )
 
 func init() {
-	core.Register(&core.Spec{
+	spec.Register(&spec.Spec{
 		Name:        "launchctl",
 		Description: "Service or domain target",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "bootstrap", Description: "Bootstraps a domain or a service into a domain"},
 			{Name: "bootout", Description: "Tears down a domain or removes a service from a domain"},
 			{Name: "enable", Description: "Enables an existing service"},
@@ -59,7 +59,7 @@ func init() {
 			{Name: "version", Description: "Prints the launchd version"},
 			{Name: "help", Description: "Prints the usage for a given subcommand"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "-w", Description: "Enable if disabled"},
 			{Name: "-F", Description: "Force load"},
 			{Name: "-S", Description: "Session"},