Result Types in Requests, Thread safe, Mock Engine and Providers.

1. WebServiceRequesting.requestKey as optional. If Request as Equatable or Hashable, requestKey = request, else nil.
2. WebServiceRequesting now is generic protocol and require Result Type.
3. WebServiceResponse now is generic and can convert response to concrete type. Closures in WebService now use WebServiceRequesting.ResultType as information for response type.
4. WebService class now full thread safe.
5. Added WebServiceMockEngine for emulator data from server.
6. Support Custom and Request Providers.

Warning!
After update from 2.1 to 2.2 your project compile have errors. Update your code for use 2.2.
Fast update requests: WebServiceRequesting replace to WebServiceBaseRequesting (no generic).