Fixes #88 multivalue comparison

It should now be possible to query for multivalue properties.

Tests now still fails because of a difference between jackrabbit and doctrine-dbal. The first returns a concatenated string, doctrine-dbal returnd sn sttsy.

For that reason we changed the test to support both return values. 
Fot the updated tests see: https://github.com/phpcr/phpcr-api-tests/pull/108