NSDictionary+MK passes tests.
NSDate+MK_Creation passes tests.
NSDate+MK_Manipulation passes tests.
Refactored NSDate+MK_Manupulation.
Added dateByAdding weeks, months and years.
Added subtraction for days, weeks, months and years.
Added LINQ to MKFoundation header.
Merge branch 'release/0.2.0'