Add two convenience methods

- These are used to quickly extract specific streams. For example, you
can now quickly get the highest stream URL or the lowest stream URL.

YTVimeoExtractor/YTVimeoVideo.h

@@ -114,5 +114,19 @@ typedef NS_ENUM(NSUInteger, YTVimeoVideoQuality) {
  *  A `NSDictionary` object that contains all the metadata about the video.
  */
 @property (nonatomic, readonly) NSDictionary *__nullable metaData;
+/**
+ *  Convenience method to get the highest quality stream URL.
+ *
+ *  @see YTVimeoVideoQuality
+ *  @return The highest quality stream URL.
+ */
+-(NSURL *__nullable)highestQualityStreamURL;
+/**
+ *  Convenience method to get the lowest quality stream URL.
+ *
+ *  @see YTVimeoVideoQuality
+ *  @return The lowest quality stream URL.
+ */
+-(NSURL *__nullable)lowestQualityStreamURL;
 
 @end

YTVimeoExtractor/YTVimeoVideo.m

@@ -110,6 +110,20 @@ - (void)extractVideoInfoWithCompletionHandler:(void (^)(NSError *error))completi
     });
 }
 
+#pragma mark -
+-(NSURL *)highestQualityStreamURL{
+
+    NSURL *url = self.streamURLs[@(YTVimeoVideoQualityHD1080)] ?: self.streamURLs[@(YTVimeoVideoQualityHD720)] ?: self.streamURLs [@(YTVimeoVideoQualityMedium480)]?: self.streamURLs[@(YTVimeoVideoQualityMedium360)]?:self.streamURLs[@(YTVimeoVideoQualityLow270)];
+
+    return url;
+}
+
+-(NSURL *)lowestQualityStreamURL{
+
+    NSURL *url = self.streamURLs[@(YTVimeoVideoQualityLow270)] ?: self.streamURLs[@(YTVimeoVideoQualityMedium360)] ?: self.streamURLs [@(YTVimeoVideoQualityMedium480)]?: self.streamURLs[@(YTVimeoVideoQualityHD720)]?:self.streamURLs[@(YTVimeoVideoQualityHD1080)];
+
+    return url;
+}
 
 #pragma mark - NSObject
 - (NSString *) description