Add ForceEqualSignAlignment to .rubocop.yml (#1190)

* Add ForceEqualSignAlignment to .rubocop.yml

* Revert ForceEqualSignAlignment cop

* Update method alignment

* Undo addition of whitespace to improve readability

* Fix missing alignment

lib/liquid/forloop_drop.rb

@@ -3,10 +3,10 @@
 module Liquid
   class ForloopDrop < Drop
     def initialize(name, length, parentloop)
-      @name = name
-      @length = length
+      @name       = name
+      @length     = length
       @parentloop = parentloop
-      @index = 0
+      @index      = 0
     end
 
     attr_reader :name, :length, :parentloop