Revert "Consider methods added via attr_* no commands"

Althugh there is an issue in here, the current implementation is
very brittle as looking into the stacktrace is not guaranteed to
stay the same across different ruby versions and ruby implementations.

This reverts commit fb149e3.

Author: José Valim

lib/thor/base.rb

@@ -119,6 +119,18 @@ def register_klass_file(klass) #:nodoc:
     end
 
     module ClassMethods
+      def attr_reader(*) #:nodoc:
+        no_commands { super }
+      end
+
+      def attr_writer(*) #:nodoc:
+        no_commands { super }
+      end
+
+      def attr_accessor(*) #:nodoc:
+        no_commands { super }
+      end
+
       # If you want to raise an error for unknown options, call check_unknown_options!
       # This is disabled by default to allow dynamic invocations.
       def check_unknown_options!
@@ -578,9 +590,6 @@ def method_added(meth)
           # Return if it's not a public instance method
           return unless public_method_defined?(meth.to_sym)
 
-          # Return if attr_* added the method
-          return if caller.first.to_s[/`attr_(reader|writer|accessor)'/]
-
           return if @no_commands || !create_command(meth)
 
           is_thor_reserved_word?(meth, :command)

spec/base_spec.rb

@@ -287,9 +287,5 @@ def hello
       expect(capture(:stderr){ MyScript.start(["some_attribute"]) }).to match(/Could not find/)
       expect(capture(:stderr){ MyScript.start(["some_attribute=", "foo"]) }).to match(/Could not find/)
     end
-
-    it "respects visibility" do
-      expect(MyScript.public_instance_methods).to_not include(:private_attribute)
-    end
   end
 end