AbstractMapper - Execute arbitrary SQL queries and return results as array

## AbstractMapper - Execute arbitrary SQL queries and return results as array

### Acceptance Criteria
1. `executeAndGetResultsAsArray` method exists in AbstractMapper.
1. Method expects any kind of a query object (or a string) and does whatever handling necessary to execute the query.
1. Method returns results as string.

### Tasks
- Implement method in AbstractMapper

### Additional Notes
- The purpose of this is to reduce code duplication. It is not uncommon that a custom query is written in a mapper for a different table than the one primarily associated with the mapper. Each time the developer has to rediscover the low-level Zend Db constructs and patterns for performing a query and getting the data as an array. Adding this method will prevent those situations from becoming speed bumps.