Update Facebook SDK 4.31.1 for iOS 11 (jeduan#634)

* Update FacebookSDKs-iOS-4.31.1

* contentTitle, imageURL and contentDescription have been deprecated in Facebook API 2.9

* Update README according deprecation

README.md

@@ -109,7 +109,11 @@ Share Dialog:
 		share_feedWeb: true, // iOS only
 	}
 
-For iOS, the default dialog mode is [`FBSDKShareDialogModeAutomatic`](https://developers.facebook.com/docs/reference/ios/current/constants/FBSDKShareDialogMode/). You can share that by adding a specific dialog mode parameter. The available share dialog modes are: `share_sheet`, `share_feedBrowser`, `share_native` and `share_feedWeb`. [Read more about share dialog modes](https://developers.facebook.com/docs/reference/ios/current/constants/FBSDKShareDialogMode/)
+#### iOS
+
+The default dialog mode is [`FBSDKShareDialogModeAutomatic`](https://developers.facebook.com/docs/reference/ios/current/constants/FBSDKShareDialogMode/). You can share that by adding a specific dialog mode parameter. The available share dialog modes are: `share_sheet`, `share_feedBrowser`, `share_native` and `share_feedWeb`. [Read more about share dialog modes](https://developers.facebook.com/docs/reference/ios/current/constants/FBSDKShareDialogMode/)
+
+`caption`, `description` and `picture` were deprecated in Facebok API [v2.9](https://developers.facebook.com/docs/graph-api/changelog/version2.9#gapi-deprecate) and therefore not supported anymore on iOS 
 
 Game request:
 

src/ios/FacebookConnectPlugin.m

@@ -272,9 +272,6 @@ - (void) showDialog:(CDVInvokedUrlCommand*)command
         // Create native params
         FBSDKShareLinkContent *content = [[FBSDKShareLinkContent alloc] init];
         content.contentURL = [NSURL URLWithString:[params objectForKey:@"link"]];
-        content.contentTitle = [params objectForKey:@"caption"];
-        content.imageURL = [NSURL URLWithString:[params objectForKey:@"picture"]];
-        content.contentDescription = [params objectForKey:@"description"];
 
         self.dialogCallbackId = command.callbackId;
         [FBSDKMessageDialog showWithContent:content delegate:self];
@@ -284,9 +281,6 @@ - (void) showDialog:(CDVInvokedUrlCommand*)command
         // Create native params
         FBSDKShareLinkContent *content = [[FBSDKShareLinkContent alloc] init];
         content.contentURL = [NSURL URLWithString:params[@"href"]];
-        content.contentTitle = params[@"caption"];
-        content.imageURL = [NSURL URLWithString:params[@"picture"]];
-        content.contentDescription = params[@"description"];
         content.hashtag = [FBSDKHashtag hashtagWithString:[params objectForKey:@"hashtag"]];
         content.quote = params[@"quote"];