Account namespace updates: part 4 (transfers, singular namespacing) (#896)

* Move Transfer to Account namespace

* Fix partial resolution due to namespacing plurality

* Make category and tag controllers consistent with namespacing convention

* Update stale partial reference

app/controllers/transaction/rules_controller.rb

@@ -0,0 +1,6 @@
+class Transaction::RulesController < ApplicationController
+  layout "with_sidebar"
+
+  def index
+  end
+end