MDL-65255 vimeo: Do not require width and height for iframe

The script for embedding videos should work without forcing width and height.
This will simplify the way we embed videos in the app.

media/player/vimeo/wsplayer.php

@@ -38,13 +38,20 @@ require_once($CFG->dirroot . '/webservice/lib.php');
 
 $token = required_param('token', PARAM_ALPHANUM);
 $video = required_param('video', PARAM_ALPHANUM);   // Video ids are numeric, but it's more solid to expect things like 00001.
-$width = required_param('width', PARAM_INT);
-$height = required_param('height', PARAM_INT);
+$width = optional_param('width', 0, PARAM_INT);
+$height = optional_param('height', 0, PARAM_INT);
 
 // Authenticate the user.
 $webservicelib = new webservice();
 $webservicelib->authenticate_user($token);
 
+if (empty($width) && empty($height)) {
+    // Use the full page. The video will keep the ratio.
+    $display = 'style="position:absolute; top:0; left:0; width:100%; height:100%;"';
+} else {
+    $display = "width=\"$width\" height=\"$height\"";
+}
+
 $output = <<<OET
 <html>
     <head>
@@ -52,7 +59,7 @@ $output = <<<OET
     </head>
     <body style="margin:0; padding:0">
         <iframe src="https://player.vimeo.com/video/$video"
-            width="$width" height="$height" frameborder="0"
+            $display frameborder="0"
             webkitallowfullscreen mozallowfullscreen allowfullscreen>
         </iframe>
     </body>