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/ops/ansible.go

@@ -1,14 +1,14 @@
 package ops
 
 import (
-	"github.com/versenilvis/iris/commands/core"
+	"github.com/versenilvis/iris/spec"
 )
 
 func init() {
-	core.Register(&core.Spec{
+	spec.Register(&spec.Spec{
 		Name:        "ansible",
 		Description: "Define and run a single Ansible task",
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "--ask-vault-pass", Description: "Ask for vault password"},
 			{Name: "--list-hosts", Description: "Outputs a list of matching hosts; does not execute"},
 			{Name: "--playbook-dir", Description: "Perform a syntax check on the playbook, but do not execute it"},