#21 Adding (currently failing) unit tests to cover scenarios where attribute is used as hashkey or more than one global secondary index
#21 Refactoring getGlobalSecondaryIndexName method to 1) Make it more readable 2) Make it lazy-evaluate the appropriate index name only once and 3) In cases where multiple global secondary indexes are eligible for use, select exact-match indexes in the first instance, or in the event of a partial index match for global hash key searches, use the first declared index in the annotation for the global hash key