OS X uploader (#252)

* Source for OS X uploader

* Readme for OS X uploader

* Export image

* .gitignore for Xcode project

* Remove redundant data

* Update readme instructions

* List formatting

* Remove personal copyright notice added by Xcode

* Added release build and updated readme

* point to doc cdn

clients/macuploader/Microbit Uploader/DirectoryWatcher.h

@@ -0,0 +1,24 @@
+#import <Foundation/Foundation.h>
+
+@class DirectoryWatcher;
+
+@protocol DirectoryWatcherDelegate <NSObject>
+
+- (void)watcher:(DirectoryWatcher*)watcher observedNewFileAtPath:(NSString*)path;
+
+@end
+
+@interface DirectoryWatcher : NSObject
+
+- (instancetype)initWithPath:(NSString*)path;
+
+@property (readonly) NSString * path;
+
+@property id<DirectoryWatcherDelegate> delegate;
+
+- (void)startWatching;
+
+//Automatically called when deallocated
+- (void)stopWatching;
+
+@end