Add validator class to verify authenticity of incoming messages
Refactor SNS Validtor class
Rename wrong exception name in DocBlock
Made cosmetic changes to the SNS Message Validator and started unit tests
Added unit tests to SNS MessageValidator
Updated the tests and code for the SNS Message Validator
Updated tests for SNS Message Validator to address remaining openssl interactions
Small update to SNS Message Validator
Refactored SNS Message Validation to be simpler
Added ext-openssl to the suggests and dev list in composer.json
Added a CHANGELOG item for the SNS Message Validator feature
Updated the APC check to throw a more specific exception