Fix Deserialization error when "extensions" contains "extra" field (#10)

* use custom deserialization to handle list extensions

* Fix parsing error when extensions contain "extra" field

Co-authored-by: Joshua Hight <joshua.hight@doordash.com>
Co-authored-by: Martin Wilhelm <martin.wilhelm@essendi.de>

Merge pull request #6 from nitram22/master

Extension allowing the use of a different certstream server

Update BoringParts.java

Added reconnect logic

update Certificate structure and readme

Update README.md