Outlined methods in headers.

Outlined the methods necessary to add support for custom store URLs.
Added Support For Custom Working Directories (1/3)

Added support to iCloud stores.
Added Support For Custom Working Directories (2/3)

Added support to standard setup.
Added Support For Custom Working Directories (3/3)

Added support to NSPersistentStoreCoordinator category.
Added test for custom working directories.
Fixed incompatible pointer types error.
Fixed URL error.
Fixed error with creating a NSURL from a path.
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
Added back public method in MagicalDataImport

Fixes #821
Merge pull request #833 from ryanjm/add-importValuesForKeysWithObject

Make `-MR_importValuesForKeysWithObject:` a public method again
Combined two functionally identical methods
Replace NSPersistentStoreCoordinator's `lock` and `unlock` methods as they are deprecated in iOS 8.0 and OS X 10.10
Restore lock/unlock under iOS 7.x and OS X 10.9
Revert! Revert! This can be fixed in MagicalRecord 3.0
Once more, with feeling…