Added HTML purifier support

Change-Id: Ic76ebc3f3fb05518d0a0427b3fe327e4269ee7a9
Signed-off-by: SJ <sj@acts.hu>

webui/system/helper/standalone/HTMLPurifier/ConfigSchema/schema/URI.SafeIframeRegexp.txt

@@ -0,0 +1,22 @@
+URI.SafeIframeRegexp
+TYPE: string/null
+VERSION: 4.4.0
+DEFAULT: NULL
+--DESCRIPTION--
+<p>
+    A PCRE regular expression that will be matched against an iframe URI.  This is
+    a relatively inflexible scheme, but works well enough for the most common
+    use-case of iframes: embedded video.  This directive only has an effect if
+    %HTML.SafeIframe is enabled.  Here are some example values:
+</p>
+<ul>
+    <li><code>%^http://www.youtube.com/embed/%</code> - Allow YouTube videos</li>
+    <li><code>%^http://player.vimeo.com/video/%</code> - Allow Vimeo videos</li>
+    <li><code>%^http://(www.youtube.com/embed/|player.vimeo.com/video/)%</code> - Allow both</li>
+</ul>
+<p>
+    Note that this directive does not give you enough granularity to, say, disable
+    all <code>autoplay</code> videos.  Pipe up on the HTML Purifier forums if this
+    is a capability you want.
+</p>
+--# vim: et sw=4 sts=4