Added the the revert, union and interception methods on the NSArray category
Small fix on the README file
Grammar fix
Small refactoring on the methods names.
Also separated the logic of the unionWithArray method. So now we have a method that removes the duplicates (uniqueObjects) and a method (arrayByMerginObjectsFromArray) that adds a new array and removes the duplicates.
Added the methods to the NSMutableArray
Merge pull request #2 from RuiAAPeres/master

Added revert, union and Interception