TASK: Allow installation with Neos 8

BUGFIX: PHP version related cleanup

Resolves: #5

BUGFIX: Prevent empty response errors

!!! FEATURE: Compatible with Neos 7

TASK: Remove testing note in readme

TASK: Add test for loadstyles from file as process

TASK: Add example for shorthand css helper

FEATURE: Implement style merging as http component

TASK: Remove abstract test helper

TASK: Add limitations to readme