Don't try to normalize URLs that are not pointing to local URLs

Right now we have 2 components:

• LocalURLResourceReferenceNormalizer which does the normalization and only does the work for local URLs
• URLNormalizerListener which finds all LinkBlocks in the page and updates them with the results from LocalURLResourceReferenceNormalizer. The problem is that it doesn't check if any normalization has happened and thus is doing too much work and lowers the performance.