Bugfix in Fog::DNS::AWS::Records.all!

If we have more than 100 AWS records, this method returns different
results if called twice. So we should reset attributes before each call.

lib/fog/aws/models/dns/records.rb

@@ -44,6 +44,11 @@ module Fog
         def all!
           data = []
 
+          merge_attributes({'NextRecordName' => nil,
+                            'NextRecordType' => nil,
+                            'NextRecordIdentifier' => nil,
+                            'IsTruncated' => nil})
+
           begin
             options = {
                 :name => next_record_name,