added editable property to fields
Merge pull request #138 from sulu-cmf/feature/editable-fields

[FEATURE] added editable property to fields
removed order by clause from count to get it working on postgres
Merge pull request #140 from sulu-cmf/bugfix/count-postgres

[BUGFIX] corrected count for postgresql
implemented different join methods
implemented join conditions
Merge pull request #143 from sulu-cmf/feature/doctrine-list-joins

[FEATURE] Implemented DoctrineJoinDescriptors
Merge branch 'develop' into feature/sort-fields

Conflicts:
	src/Sulu/Component/Rest/ListBuilder/FieldDescriptor/AbstractFieldDescriptor.php
	src/Sulu/Component/Rest/ListBuilder/FieldDescriptor/DoctrineFieldDescriptor.php