Merge branch '2.4' of github.com:Codeception/Codeception into 2.4

documentation updated

preparing 2.4.0 release

version bump

deprecated Facebook module

Added a notice that code completion requires additional package

Preparing 2.3.6 release.

Updated changelog, updated docs, updated tested Laravel project in travis

updated changelog, version dump, docs updated

updated changelog, version bump

Merge branch '2.3' of github.com:Codeception/Codeception into 2.3