Route53 Zone.update_record() fix [spulec/moto#83]

 * Zone.update_record() issues what is essentially a batched update to
   the AWS Route53 API: It's a DELETE followed by a CREATE.  This fix
   allow moto to handle that batched update.
Remove special HTTPretty install from Travis.
Merge pull request #86 from hltbra/fix-describe-images-for-missing-images

Fix DescribeImages for missing images
0.2.17
Merge pull request #87 from hltbra/ami-backend-describe_images-refactoring

Refactor AmiBackend.describe_images: make logic of missing image simpler
Fixed typo in REQUEST_POST_INSTANCES_TEMPLATE
Merge pull request #88 from sgarcialaguna/master

Fixed typo in REQUEST_POST_INSTANCES_TEMPLATE
Updated test_route53.test_rrset() for batch update

 * This should provide a test for [spulec/moto#84].
 * Prior to deleting the existing A record, it sends a batch update that
   includes DELETE and a CREATE, which is what boto performs when
   updating a ResourceRecord.
Merge pull request #84 from vrivellino/master

moto.route53.responses.rrset_response() fix for spulec/moto#83
Lock down sure version due to https://github.com/gabrielfalcao/sure/pull/46.
Fix S3 URL Regex to allow slashes in key names.
0.2.18
Implement HEAD method due to changes in boto 2.25, closes: #91
Merge pull request #92 from EvaSDK/implement-head-get-bucket

Implement HEAD method due to changes in boto 2.25, closes: #91
Add new version of boto to Travis.
Fix misconfigured version of boto.
support QueueNamePrefix in the SQS Backend
Merge pull request #97 from ossareh/master

support QueueNamePrefix in the SQS Backend
Add @ossareh to contributors.
Query order/limit enforced. Scan limit enforced