use auth_handler to specify host header value if possible
a more robust test for the function
Attempt to fix issues related to encoding of values in HTTP headers when the header contains unicode values.
Add support for new STS and IAM calls related to SAML
Add a comment about empty response bodies, change argument order in update_saml_provider to match the rest of the code.
Merge pull request #1867 from danielgtaylor/sts-iam

Add support for new STS and IAM calls related to SAML. Fixes #1867.
Add ASCII range 32-126 to the safe range when quoting headers.
Add a space to the integration test to confirm it works as expected
Merge pull request #1864 from danielgtaylor/s3-header-encoding

Fix issues related to encoding of values in HTTP headers when using unicode. Fixes #1864, #1839, #1829, #1828, #702.
Release notes and version bump for 2.18.0
Update README.rst

the release notes in the github wiki seem to be no longer maintained.
Merge pull request #1869 from robbyt/patch-1

Update README.rst
Delete the changelog.

Since it hasn't been updated in 2 years.
Merge pull request #1870 from Celc/patch-1

Delete the old changelog in favor of the README link to ReadTheDocs changelogs. Fixes #1870.
Added support for CopyDBSnapshot
Added unit tests covering RDS DBSnapshots methods
Merge pull request #1872 from juanfont/develop

Add support for RDS CopyDBSnapshot. Fixes #1872, #1865.
Remove changelog from manifest.
Add max results parameters to EC2 describe instances and describe tags calls. Also updates describe spot instance price history call with a max results parameter.
Merge pull request #1873 from danielgtaylor/ec2-max-results

Add max results parameters to EC2 describe instances and describe tags. Fixes #1873.