Add UIApplication's category with method to retrieve document directory path and URL

Signed-off-by: Luca Bernardi <luka.bernardi@gmail.com>
Add directory watcher class

Signed-off-by: Luca Bernardi <luka.bernardi@gmail.com>
Add imageNamed:bundleName:

Signed-off-by: Luca Bernardi <luka.bernardi@gmail.com>
Add UIColor category

Signed-off-by: Luca Bernardi <luka.bernardi@gmail.com>
Add [UIImage gradientImageWithColors:size:]

Signed-off-by: Luca Bernardi <luka.bernardi@gmail.com>
Add [NSFileManager addSkipBackupAttributeToFileAtURL:]

Signed-off-by: Luca Bernardi <luka.bernardi@gmail.com>
Merge branch 'master' of https://github.com/lukabernardi/LBKit