Add ps:scale (#24)

* Add ps:scale

* Update ps.rb

* Update README.md

README.md

@@ -88,6 +88,8 @@ Commands:
   dokku ps:rebuild                                 # Rebuild the app
   dokku ps:restart                                 # Restart the app container
   dokku ps:start                                   # Start the app container
+  dokku ps:scale                                   # List the current scale of Procfile processes
+  dokku ps:scale proc1=scale1 [proc2=scale2 ...]   # Scale one or more Procfile processes
   dokku run <cmd>                                  # Run a one-off command in the environment of the app
   dokku ssh                                        # Start an SSH session as root user
   dokku url                                        # Show the first URL for the app

lib/dokku_cli/ps.rb

@@ -4,7 +4,8 @@ class Cli < Thor
     map "ps:rebuild" => "ps_rebuild",
         "ps:restart" => "ps_restart",
         "ps:start" => "ps_start",
-        "ps:stop" => "ps_stop"
+        "ps:stop" => "ps_stop",
+        "ps:scale" => "ps_scale"
 
     desc "ps", "List processes running in app container(s)"
     def ps
@@ -30,5 +31,14 @@ def ps_start
     def ps_stop
       run_command "ps:stop #{app_name}"
     end
+
+    desc "ps:scale", "Scale the app processes"
+    def ps_scale(*processes)
+      if processes.empty?
+        run_command "ps:scale #{app_name}"
+      else
+        run_command "ps:scale #{app_name} #{processes.join(' ')}"
+      end
+    end
   end
 end