added tests

added testIdentifier
added documentation
cs fixes
event no longer inherits logger
included traits for eventHandler

removed more unecessary code
cs fixes
new test for event multiple handlers
removed use mockery statements
removed unnecessary use statements
added parent::__construct() to SnsEventHandler for consistency with Monolog handler behaviour
refactor and rename DynamoDbSecondaryIndexProcessor
add extra test for above

rename class

updated class name in tests
removed EventHandlerTrait
reinstated 5.3 support
removed static timezone property from Event
removed return value from Event constructor