Merge pull request pusher#183 from pusher/end-to-end-encryption

End to end encryption

remove logging of expected signature

Merge pull request pusher#168 from pusher/wh-validation

Add pusher signature validation

Add versions 3.0.1, 3.0.2 and 3.0.3 to CHANGELOG

Merge pull request pusher#150 from mn7z/master

Check curl handle explicitly for resource type instead of null.

Minor logging changes to separate info from errors

Releasing version 3.0.0 with Namespaces

Improve curl error logging

Add 'curl_options' support