updated changelog, updated docs

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