Unified2

* update Eventto_h for faster db insert

* Add to_h method for core classes
* Add to_pacp/to_file method for packet class

* update deps
* added support for unified2 extra data
* refactor Unified2read & Unified2watch
* Interrupt now returns file position
* updated spec for legacy u2 and current format changes
* events can now have multiple packets
* bug fixes and documentation

* update packetfu ~> 1.1
* update bindata ~> 1.4
* update hexdump ~> 0.2
* remove pcaprb dep

* remove unnecessary file (untitled.rb)

* Add payload checksum support