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/defaults.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:        "defaults",
 		Description: "Global domain",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "read", Description: "Shows defaults"},
 			{Name: "write", Description: "Writes key for domain"},
 			{Name: "delete", Description: "Deletes domain or key in domain"},
@@ -19,7 +19,7 @@ func init() {
 			{Name: "help", Description: "Show help text"},
 			{Name: "read-type", Description: "Shows the type for the given domain, key"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "-globalDomain", Description: "Global domain"},
 			{Name: "-app", Description: "Application name"},
 			{Name: "-string", Description: "Command line interface to a user's defaults"},