Fix parsing GetProductCategoriesForASIN response

The amazon mws GetProductCategoriesForASIN api call
returns multiple <Self> nodes (if available), but
the code returned only the last XML node.
fixup! Fix parsing GetProductCategoriesForASIN response
fixed get_all_adjustment_types for ec2/autoscale

Signed-off-by: Pascal Hakim <pasc@redellipse.net>
added adjustment types unit test

Signed-off-by: Pascal Hakim <pasc@redellipse.net>
Actually check results in TestGetAdjustmentTypes unit test
Fixed up some sphinx syntax in inline docs for route53
Remove route53 documentation build warnings
Added a basic route53 tutorial
Fix docs for get_queue_attributes

This does not actually delete the queue.
Merge pull request #2060 from pasc/route53_tutorial_start

Added a basic route53 tutorial
Merge pull request #2061 from xb95/develop

Fix docs for get_queue_attributes
Added some basic unit tests for route53
Added some missing __repr__() methods to cloudfront
Merge pull request #2024 from ckrybus/fix-mws-get-product-categories

Fix parsing GetProductCategoriesForASIN response. Fixes #2024.
Merge pull request #2059 from pasc/route53_docs_cleanup

Minor fixes for Route53 docs cleanup
Merge remote-tracking branch 'pasc/cloudfront_repr' into develop
Fixes #2069.
Merge remote-tracking branch 'pasc/route53_unit_tests' into develop
Fixes #2066.
Merge remote-tracking branch 'pasc/autoscale_get_all_adjustment_types' into develop
Fixes #2058, #1538.