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/js/ganache_cli.go

@@ -1,14 +1,14 @@
 package js
 
 import (
-	"github.com/versenilvis/iris/commands/core"
+	"github.com/versenilvis/iris/spec"
 )
 
 func init() {
-	core.Register(&core.Spec{
+	spec.Register(&spec.Spec{
 		Name:        "ganache-cli",
 		Description: "Fast Ethereum RPC client",
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "-a", Description: "Specify the number of accounts to generate at startup"},
 			{Name: "-e", Description: "Amount of ether to assign each test account. Default is 100"},
 			{Name: "-b", Description: "Generate deterministic addresses based on a pre-defined mnemonic"},