Revert "removed dependency celements-core"

This reverts commit db50084a6c7974128aefbf7e565a1eb08e44d645.
added LuceneSearchService.createSpace/Object/FieldRestriction
renamed LuceneQueryApi to LuceneQuery and LuceneQueryRestrictionApi to
QueryRestriction
added interface IQueryRestriction and implemented QueryRestrictionGroup
LuceneQuery adds databse as restriction when creating object
tests added and fixed
added deprecated methods back in to ensure backwards compatibility
added LuceneSearchService.createRestrictionGroup()
Merge pull request #1 from celements/restriction-groups

Restriction groups