Added UIButton+WebCache category

+/*
+ * This file is part of the SDWebImage package.
+ * (c) Olivier Poitrey <rs@dailymotion.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+#import "SDWebImageCompat.h"
+#import "SDWebImageManagerDelegate.h"
+
+@interface UIButton (WebCache) <SDWebImageManagerDelegate>
+
+- (void)setImageWithURL:(NSURL *)url;
+- (void)setImageWithURL:(NSURL *)url placeholderImage:(UIImage *)placeholder;
+- (void)cancelCurrentImageLoad;
+
+@end

+/*
+ * This file is part of the SDWebImage package.
+ * (c) Olivier Poitrey <rs@dailymotion.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+#import "UIButton+WebCache.h"
+#import "SDWebImageManager.h"
+
+@implementation UIButton (WebCache)
+
+- (void)setImageWithURL:(NSURL *)url
+{
+    [self setImageWithURL:url placeholderImage:nil];
+}
+
+- (void)setImageWithURL:(NSURL *)url placeholderImage:(UIImage *)placeholder
+{
+    SDWebImageManager *manager = [SDWebImageManager sharedManager];
+
+    // Remove in progress downloader from queue
+    [manager cancelForDelegate:self];
+
+    [self setImage:placeholder forState:UIControlStateNormal];
+
+    if (url)
+    {
+        [manager downloadWithURL:url delegate:self];
+    }
+}
+
+- (void)cancelCurrentImageLoad
+{
+    [[SDWebImageManager sharedManager] cancelForDelegate:self];
+}
+
+- (void)webImageManager:(SDWebImageManager *)imageManager didFinishWithImage:(UIImage *)image
+{
+    [self setImage:image forState:UIControlStateNormal];
+}
+
+@end