Saving content in 2 locales without flushing will raise a unique constraint error

[alexander-schranz]

As written in #35. If content is saved in en and then saved in de it will at the following line create 2 unlocalizedDimension data with the same dimension attributes, when flushing this will end in a uniqueConstraint error.

SuluContentBundle/Content/Application/DimensionContentCollectionFactory/DimensionContentCollectionFactory.php

Lines 73 to 77 in 29afa52

	$unlocalizedDimensionContent = $this->createContentDimension(
	$contentRichEntity,
	$dimensionContents,
	$unlocalizedAttributes
	);

This should be avoided by creating maybe an in memory cache. We have a similiar issue with the TagFactory here #176