Lucene support for partial patient identifier searches

Background :

As part of TRUNK-425 OpenMRS now leverages on lucene for patient searches. Currently OpenMRS only performs searches on full identifier matches. We could maintain this as the default behavior but add a functionality to support partial matches. As mentioned here , we can add support for partial identifier searches if the search global property is set to start or anywhere.

A better functionality would also be to separate the findPatients method  to support separate  searching by identifier, name and other attributes.