Add naive cli command router

src/cli/command_router.cr

@@ -0,0 +1,17 @@
+class CLI::CommandRouter
+  def initialize
+    @mappings = [] of {String, Proc(Nil)}
+  end
+
+  def add(route, &block)
+    @mappings.push({route, block})
+  end
+
+  def handle(command)
+    @mappings.each do |i|
+      if i[0] == command
+        i[1].call
+      end
+    end
+  end
+end