Update load order of shared credentials file on Windows

Use USERPROFILE then HOMEDRIVE/HOMEPATH

Fixes #315
Add tests for Amazon CloudWatch Logs (AWS.CloudWatchLogs)
Update EC2 tests for new API version
Update to aws-sdk-apis@3.1+
Support model names with dashes in them
Double URI-encode path component for canonical string (non-S3 services)
Allow setting custom separator on uniqueName()
Add support for Amazon Cognito Sync and Identity services
Fix RDS pagination test
Update supported services lists
Tag release v2.0.6

References:
  #312, #315
Tag release v2.0.6

References:
  #312, #315
Merge release branch into master