osx: fix client compatibility

Xcode does not warn when using unavailable APIs on older SDKs.
After recompiling against the 10.8 SDK, errors appeared across the
client.

- NSButton.highlight state has been added in OSX 10.10
- window.beginSheet has been added in OSX 10.9
- window.keyWindow has been added in OSX 10.10
- NSViewController.viewDidLoad has been added in OSX 10.10
- NSString.containsString has been added in OSX 10.10

Change-Id: I9c4e271f49711570859d85d43608cf8edf294e01
Tuleap: #343
diff --git a/src/delegates/ImageManipulationDelegate.mm b/src/delegates/ImageManipulationDelegate.mm
index f3a67da..30e916e 100644
--- a/src/delegates/ImageManipulationDelegate.mm
+++ b/src/delegates/ImageManipulationDelegate.mm
@@ -126,7 +126,7 @@
 
     QPixmap ImageManipulationDelegate::drawDefaultUserPixmap(const QSize& size, bool displayPresence, bool isPresent) {
         // create the image somehow, load from file, draw into it...
-        auto sourceImgRef = CGImageSourceCreateWithData((CFDataRef)[[NSImage imageNamed:@"default_user_icon"] TIFFRepresentation], NULL);
+        auto sourceImgRef = CGImageSourceCreateWithData((__bridge CFDataRef)[[NSImage imageNamed:@"default_user_icon"] TIFFRepresentation], NULL);
         auto imgRef = CGImageSourceCreateImageAtIndex(sourceImgRef, 0, NULL);
         auto finalpxm =  QtMac::fromCGImageRef(resizeCGImage(imgRef, size));
         CFRelease(sourceImgRef);