(dev/core#647) Fix Up Contact Selector Test by changing class name to get test to...

(dev/core#647) Fix Up Contact Selector Test by changing class name to get test to run and make changes following code changes that affect clauses and calling get rows

CRM_Contact_SelectorTest - Fix escaping

(dev/core#217) CRM_Contact_SelectorTest - Remove stale/unnecessary assertion

The table `civicrm_prevnext_cache` includes three columns (`entity_id1`,
`entity_id2`, `entity_table`).  These columns have some use-cases (e.g.  for
deduping) and some historical value, but the only one needed for
caching search-results is `entity_id1`.

dev/core#217 introduced an interface `CRM_Core_PrevNextCache_Interface` for
caching search-results.  This interface only passes through a list of CID's
(effectively `entity_id1`); because we don't need `entity_id2` and
`entity_table`, it makes no provisions for passing them through, and they're
not saved.  This simplifies the interface and makes it more realistic to
implement alternative prevnext storage mechanisms.