1-join-leave: added

lib/release/join.rb

@@ -0,0 +1,24 @@
+require_relative './base'
+
+module Release
+
+  class Join < Release::Base
+    def valid?
+      argv.size == 2
+    end
+
+    def help
+      "release join version"
+    end
+
+    def execute
+      subcommand, version = *argv
+
+      validate_current_branch_master
+      git_pull current_branch
+
+      git_checkout_track release_branch_from_version(version)
+    end
+  end
+
+end