Merge pull request thephpleague#234 from quetzyg/fix/json-api-seriali…

…zer-visibility

[RFC] Extending JSON API Serializer

Released 0.12

Added thephpleague#126 to CHANGELOG

Added 0.10.0 changes

Updated changelog for 0.9.1.

Updated changelog/readme for 0.9.0.

Added changelog for 0.8.3.

Fixed Invalid argument supplied for foreach()

Changelog for 0.8.1

Updated README and whatnot.