Merge pull request #784 from eventhorizonpl/fix_docs

fix documentation warnings p1
Conflicts:
	docs/en/reference/advanced-configuration.rst
[DDC-3120] Fix bug with unserialize bc break in PHP 5.4.29 and PHP 5.5.13
Fix wrong version
The proxy factory always expects non-null identifier values
Release 2.4.3
Bump version to 2.4.4
DDC-3208 - hotfix for DDC-3160 backported to 2.4.x
Merge branch 'hotfix/DDC-3208-backport-DDC-3160' into 2.4
Release 2.4.4
Bump version to 2.4.5