Modify Faker::Internet.slug (#1136)

* Modify Modify Faker::Internet.slug

Before: slug('Something Co., Ltd.','-')
 => "something-co.,-ltd."

After: slug('Something Co., Ltd.','-')
 => "something-co-ltd"

* Add test for unwanted slug content i.e. extraneous commas and full stops.

lib/faker/internet.rb

@@ -167,7 +167,7 @@ def url(host = domain_name, path = "/#{user_name}", scheme = 'http')
 
       def slug(words = nil, glue = nil)
         glue ||= sample(%w[- _ .])
-        (words || Faker::Lorem.words(2).join(' ')).gsub(' ', glue).downcase
+        (words || Faker::Lorem::words(2).join(' ')).delete(',.').gsub(' ', glue).downcase
       end
 
       def device_token

test/test_faker_internet.rb

@@ -217,6 +217,10 @@ def test_slug_with_content_arg
     assert @tester.slug('Foo bAr baZ').match(/^foo(_|\.|\-)bar(_|\.|\-)baz$/)
   end
 
+  def test_slug_with_unwanted_content_arg
+    assert @tester.slug('Foo.. bAr., baZ,,').match(/^foo(_|\.|\-)bar(_|\.|\-)baz$/)
+  end
+
   def test_slug_with_glue_arg
     assert @tester.slug(nil, '+').match(/^[a-z]+\+[a-z]+$/)
   end