Fixed options not being passed through to Hijacker

Bugfix release, moving from alpha to stable state

Status: **Ready for merge**
Reviewers: @scalvert @tedtate 

## Changes
- Fixed invocation options not being passed through to the Hijacker instance
- Added documentation for custom data parsers
- Changed the way we guard the readyStateHandler
Are all these parameters required? Is there a case where we want to create a hijacker but not immediately specifying the callbacks. 

I would also rename that cbs variable to something more meaningful.