Added test for own queue async testing and removed a over complicated test method
Use the TSAsyncTesting pod after extracting it.
Corrected spelling misstake.
Minor refactoring, removed the shared instance. It is now up to the user to create a singleton if they want to or pass the core data object around.

Also removed the Thread property from a context. Was not a good idea.
Added basic tests for in memory core data stack.
Merge branch 'feature/thread_aware_contexts' into develop
Merge branch 'release/0.1'