Get / Update mocking

**Mocking Updates:**
* Reworked mock data to dynamically match service definition
* Implemented mock services as singletons
* Mocked data requests (e.g. MapServer/0/1)
* Mocked query requests (e.g. MapServer/0/query)

**Testing updates:**
* Update mocking setup
* Improve *_initStore* asynchronous tests
* Implement *get* tests

**Store updates:**
* Created wrapper to wait for initialization
* Implement *get* function