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/pmset.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:        "pmset",
 		Description: "Display sleep timer (value in minutes, or 0 to disable)",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "live", Description: "Display the settings currently in use. (default if no argument given)"},
 			{Name: "custom", Description: "Display custom settings for all power sources"},
 			{Name: "cap", Description: "Display which power management features the machine supports"},
@@ -31,7 +31,7 @@ func init() {
 			{Name: "schedule", Description: "For setting up one-time power events"},
 			{Name: "repeat", Description: "For setting up daily/weekly power on and power off events"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "-g", Description: "GETTING"},
 			{Name: "-a", Description: "Settings for all"},
 			{Name: "-b", Description: "Settings for battery"},