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/firebase.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:        "firebase",
 		Description: "ProjectAlias",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "appdistribution:distribute", Description: "Upload a distribution"},
 			{Name: "apps:android:sha:create", Description: "Add a SHA certificate hash for a given app id"},
 			{Name: "apps:android:sha:delete", Description: "Delete a SHA certificate hash for a given app id"},
@@ -60,7 +60,7 @@ func init() {
 			{Name: "login:use", Description: "Set the default account to use for this project directory"},
 			{Name: "logout", Description: "Log the CLI out of Firebase"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "--app", Description: "The app id of your Firebase app"},
 			{Name: "--release-notes", Description: "Release notes to include with this distribution"},
 			{Name: "--release-notes-file", Description: "Path to file with release notes to include with this distribution"},