some coding about querying
* now filterBy is queryBuilder and is more general purpose
* it now exports two functions, one of which is the ex-buildQuery function
 from handleGet
* table selection moved at invocation level
tuned error codes and added a check for malformed URL
added support for string-only queries; non-MySQL errors are now flushed down the promise chain
Enhanced PUT requests handling
* support for linked resources
* removed squel-mocking thanks to the improvements in Carpenter.callQuery
* added check for actual need to have IDs, useful for linked resources
minor improvements to jsonError object building