rubocop: fix various style issues.

app/logical/user_name_validator.rb

@@ -1,7 +1,7 @@
 class UserNameValidator < ActiveModel::EachValidator
   def validate_each(rec, attr, value)
-  	name = value
-  	
+    name = value
+
     rec.errors[attr] << "already exists" if User.find_by_name(name).present?
     rec.errors[attr] << "must be 2 to 100 characters long" if !name.length.between?(2, 100)
     rec.errors[attr] << "cannot have whitespace or colons" if name =~ /[[:space:]]|:/