Developer can define MR_LOGGING_CONTEXT to log MagicalRecord entries in specific context in  Lumberjack.
Added missing import to MagicalRecordShorthand.h.
Changed occurences of MR_DEPRECATED_WILL_BE_REMOVED_IN_3_0 to MR_DEPRECATED_WILL_BE_REMOVED_IN("3.0")
Merge pull request #830 from CraigSiemens/feature/shorthand-build-failure

Fix shorthand imports, and deprecation macros
Merge pull request #827 from jozefizso/feature_mr_logging_context

Add MR_LOGGING_CONTEXT to allow the developer to set a Cocoa Lumberjack context when logging (defaults to 0)
Perform MR_workingName activity on the context's queue