[Contributing] New PR and commit reqs.

Introducing new pull request and commit requirements.
fix #253
sort out block introduction and custom block tutorial
Merge pull request #416 from symfony-cmf/block-service-cleanup

sort out block introduction and custom block tutorial
Reverted 1.1 features
Fixed wrong revertions mentioned by @dbu
Update the_model.rst

When installing via composer as per the documentation, the example does not work with phpcr-odm 1.0. It is necessary to add use Doctrine\Common\DataFixtures\OrderedFixtureInterface;, implement both the FixtureInterface and OrderedFixtureInterface classes and specify a getOrder function with a value larger than that in LoadSimpleCmsData.php, otherwise the following error message is thrown when running php app/console running doctrine:phpcr:fixtures:load:

Property "parent" mapped as ParentDocument may not be empty in document of
class "Symfony\Cmf\Bundle\SimpleCmsBundle\Doctrine\Phpcr\Page"
Update the_model.rst

Fixing typo
Merge pull request #428 from rodrigorigotti/patch-1

Update the_model.rst
Merge pull request #427 from coxwebdesign/patch-1

Update the_model.rst
Ported DoctrineCacheBundle to master
Title typo
Merge pull request #431 from TheMelter/master

Title typo
Fixed grammar.
Merge pull request #432 from TheMelter/master

Fixed grammar.
Update getting-started.rst

Doctrine\Bundle\PHPCRBundle\Initializer\GenericInitializer has two required parameters.
What do you think ?
Merge pull request #433 from benoitMariaux/patch-2

Update getting-started.rst
Fixed mismatching namespace
Merge pull request #434 from TheMelter/master

Fixed mismatching namespace
Grammar fix for ChainRouter page