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/cc/bazel.go

@@ -1,19 +1,19 @@
 package cc
 
 import (
-	"github.com/versenilvis/iris/commands/core"
+	"github.com/versenilvis/iris/spec"
 )
 
 func init() {
-	core.Register(&core.Spec{
+	spec.Register(&spec.Spec{
 		Name:        "bazel",
 		Description: "Bazel target",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "run", Description: "Runs the specified target"},
 			{Name: "test", Description: "Builds and runs the specified test targets"},
 			{Name: "build", Description: "Builds the specified targets"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "--autodetect_server_javabase", Description: "Back to the local JDK for running the bazel server and instead exits"},
 			{Name: "--nobatch", Description: "Run with a server"},
 			{Name: "--batch_cpu_scheduling", Description: "Only on Linux; use 'batch' CPU scheduling for Bazel"},