BackendModel::insertExtra integrated
insertExtra used in different modules

ContentBlocks, Faq, FormBuilder and Location now use
BackendModel::insertExtra()
Merging master
Changelog updated
Optional removed
Updated comments
Using $formId instead of $newId
Removed comment in Location Model
Merge branch 'BackendModel-insertExtra' of git://github.com/jeroendesloovere/forkcms into jeroendesloovere-BackendModel-insertExtra

Conflicts:
	CHANGELOG.md
	src/Backend/Modules/Location/Engine/Model.php
Cleanup comments and code in PR.
Merge branch 'jeroendesloovere-BackendModel-insertExtra'