Properly close Youtube iframes

The HTML standard only allows for specific tags that can be empty and
self-closing. Tags like <script> and <iframe> are not in that list.
While the browser renderer will let these slide, Javascript libraries
like Bootstrap and jQuery might break things because, per spec, the
iframe tag can't be self closing.

lib/bb-ruby.rb

@@ -183,14 +183,14 @@ module BBRuby
     'YouTube' => [
       /\[youtube\](.*?)\?v=([\w\d\-]+).*?\[\/youtube\]/im,
       # '<object width="400" height="330"><param name="movie" value="http://www.youtube.com/v/\2"></param><param name="wmode" value="transparent"></param><embed src="http://www.youtube.com/v/\2" type="application/x-shockwave-flash" wmode="transparent" width="400" height="330"></embed></object>',
-      '<iframe id="ytplayer" type="text/html" width="640" height="390" src="http://www.youtube.com/embed/\2" frameborder="0"/>',
+      '<iframe id="ytplayer" type="text/html" width="640" height="390" src="http://www.youtube.com/embed/\2" frameborder="0"></iframe>',
       'Display a video from YouTube.com',
       '[youtube]http://youtube.com/watch?v=E4Fbk52Mk1w[/youtube]',
       :video],
     'YouTube (Alternative)' => [
       /\[youtube\](.*?)\/v\/([\w\d\-]+)\[\/youtube\]/im,
       # '<object width="400" height="330"><param name="movie" value="http://www.youtube.com/v/\2"></param><param name="wmode" value="transparent"></param><embed src="http://www.youtube.com/v/\2" type="application/x-shockwave-flash" wmode="transparent" width="400" height="330"></embed></object>',
-      '<iframe id="ytplayer" type="text/html" width="640" height="390" src="http://www.youtube.com/embed/\2" frameborder="0"/>',
+      '<iframe id="ytplayer" type="text/html" width="640" height="390" src="http://www.youtube.com/embed/\2" frameborder="0"></iframe>',
       'Display a video from YouTube.com (alternative format)',
       '[youtube]http://youtube.com/watch/v/E4Fbk52Mk1w[/youtube]',
       :video],

test/bb-ruby_test.rb

@@ -143,8 +143,8 @@ def test_image_link
   def test_youtube
     # Uncomment below if using 4:3 format youtube video embed
     # assert_equal assert_equal '<iframe id="ytplayer" type="text/html" width="320" height="265" src="http://www.youtube.com/embed/E4Fbk52Mk1w" frameborder="0"/>', '[youtube]http://youtube.com/watch?v=E4Fbk52Mk1w[/youtube]'.bbcode_to_html
-    assert_equal '<iframe id="ytplayer" type="text/html" width="640" height="390" src="http://www.youtube.com/embed/E4Fbk52Mk1w" frameborder="0"/>', '[youtube]http://youtube.com/watch?v=E4Fbk52Mk1w[/youtube]'.bbcode_to_html
-    assert_equal '<iframe id="ytplayer" type="text/html" width="640" height="390" src="http://www.youtube.com/embed/E4Fbk52Mk1w" frameborder="0"/><iframe id="ytplayer" type="text/html" width="640" height="390" src="http://www.youtube.com/embed/abc123" frameborder="0"/>', '[youtube]http://youtube.com/watch?v=E4Fbk52Mk1w[/youtube][youtube]http://youtube.com/watch?v=abc123[/youtube]'.bbcode_to_html
+    assert_equal '<iframe id="ytplayer" type="text/html" width="640" height="390" src="http://www.youtube.com/embed/E4Fbk52Mk1w" frameborder="0"></iframe>', '[youtube]http://youtube.com/watch?v=E4Fbk52Mk1w[/youtube]'.bbcode_to_html
+    assert_equal '<iframe id="ytplayer" type="text/html" width="640" height="390" src="http://www.youtube.com/embed/E4Fbk52Mk1w" frameborder="0"></iframe><iframe id="ytplayer" type="text/html" width="640" height="390" src="http://www.youtube.com/embed/abc123" frameborder="0"></iframe>', '[youtube]http://youtube.com/watch?v=E4Fbk52Mk1w[/youtube][youtube]http://youtube.com/watch?v=abc123[/youtube]'.bbcode_to_html
   end
 
   def test_vimeo