Add flash helper

Closes #120

Author: joeldrapper

lib/phlex/rails/helpers.rb

@@ -465,6 +465,13 @@ module FileFieldTag
 		define_output_helper :file_field_tag
 	end
 
+	module Flash
+		extend Phlex::Rails::HelperMacros
+
+		# @!method flash(...)
+		define_value_helper :flash
+	end
+
 	module FontPath
 		extend Phlex::Rails::HelperMacros