Update PageAdmin.php

When you add your custom admin for page, SonataPageBundle's is throwing exception.
Merge pull request #359 from Warxcell/patch-1

Update PageAdmin.php
Update PageAdmin.php

The admin is throwing exception when you have your own admin for blocks (Too many admins registered).
Update BlockAdmin.php

The admin is throwing exception when you have your own admin for blocks (Too many admins registered).
change to null instead of false on getting the parent and target page
Merge pull request #361 from Warxcell/patch-4

Update BlockAdmin.php
Merge pull request #362 from Warxcell/patch-3

Update PageAdmin.php
[FIX] Trad
Merge pull request #364 from Th3Mouk/patch-1

[FIX] Trad
[ADD] Missing Label
Merge pull request #366 from Th3Mouk/master

[ADD] Missing Label
Merge pull request #363 from idhard/master

change to null instead of false on getting the parent and target page