Wp 703 find services refinements

PendingOperation constructor now takes cancel function parameter, for better information hiding. Don't use delete, garbage collection will take case of unreferenced objects. Store rpc request instead of pendingOp in callerCache. DOMError uses name instead of type property.

Add tests for PendingOperation, AbortError, TimeoutError.

http://jira.webinos.org/browse/WP-703