Make connection pooling port-aware, properly use port settings when creating new connections.
Modify DynamoDB2 code to properly set host HTTP header and use the configured host parameter when making connections.
Make sure host is always passed as just the hostname excluding the port; set the port via http connection factory arguments
Add unit tests for auth v4 signing with localhost and testing connection pooling with different ports
Simplify connection pooling test
Merge pull request #1764 from danielgtaylor/pooling-port

Make HTTP(S) Connection Pooling Port-Aware. Fixes #1764, #1737.