* [aws-c-common]Upgrade to 0.4.15
* [aws-c-common]Fix cmake target path.
* [aws-c-event-stream]Upgrade to 0.1.4
* [aws-checksums]Upgrade to 0.1.5
[aws-c-event-stream]Fix cmake target path.
[aws-lambda-cpp]Upgrade to 0.2.4
[aws-sdk-cpp]Upgrade to 1.7.214
* [aws=sdk-cpp]Set feature AWSMigrationHub to lowercase.
* [aws-lambda-cpp] Drop support with OSX
