php 7.3 compatibility

change autoload to psr-4

add autoloads

changecomposer json

changecomposer json

Tagging as 2.2.1.

Merge pull request zencoder#19 from zencoder/remove_ca_cert_bundle

Bumping version to 2.2.0

Version 2.1.2

Add support for streams, and uses new phpDocumentor style