Miscellaneous Improvements

Merge pull request #14 from cfxmarkets/v1.4.x

Releasing v1.4.4

Upgrade to PHP7.1

Adapted library to work with PHP7.1

Fixed consistency issues in seralization handling

Merge pull request #5 from cfxmarkets/v1.2.x

Request to release v1.2.1

Add `refresh` method to resource and lots of bugfixes

This release adds a refresh method to JsonApi resources. It also fixes many bugs, including serializing non-initialized resources and adding certain methods to the ResourceInterface.

All implemented tests are working.