dev/core#720 add unit test, remove legacy code style.

dev/core#720 add unit test, remove legacy code style.

This PR adds tests to the summaryQuery code in preparation for changes.

The one non-test change is to remove the & from summaryContribution fn.

It is only called from one place in the code & that place does not return as reference.

```
  /**
   * @return mixed
   */
  public function getSummary() {
    return $this->_query->summaryContribution($this->_context);
  }
```