Added new tests to MKCoreDataStoreIntegrationTests that use real CoreData objects instead of mocks.
Merge branch 'feature/backing_store' into develop
* [MKCoreDataStore] Added a method to fetch all operations
* [MKOperationHeap] Added a class for holding operations in memory using a binary heap
* Added a method for adding operations to an operation heap
* Added a wrapper class that decorates operations with timestamp and priority
Merge pull request #4 from marcinkuptel/feature/core_implementation

Feature/core implementation
Merge pull request #5 from marcinkuptel/develop

Develop