Attempt to fix issues related to encoding of values in HTTP headers when the header contains unicode values.
Shifted CloudWatch to SigV4.
Merge branch 'cloudwatch-sigv4' into develop
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