issue: iFrame Single Quotes

It's all about the single quotes baby! Apparently I can't read; the single
quotes are only meant for word options such as `'self'` and `'none'`. When
adding single quotes to the `<host-source>` options it takes them
literally…too literally. For example, if your options are `'localhost:80
localhost:8080 localhost:8000'` then `'localhost:80` and `localhost:8000'` will
be seen as "invalid" due to the single quotes. This removes the single
quotes from every line that sets the CSP so all options are valid. This also
adds single quotes around the `self` option so it stays valid as well.

include/client/header.inc.php

@@ -6,7 +6,7 @@ $signin_url = ROOT_PATH . "login.php"
 $signout_url = ROOT_PATH . "logout.php?auth=".$ost->getLinkToken();
 
 header("Content-Type: text/html; charset=UTF-8");
-header("Content-Security-Policy: frame-ancestors '".$cfg->getAllowIframes()."';");
+header("Content-Security-Policy: frame-ancestors ".$cfg->getAllowIframes().";");
 
 if (($lang = Internationalization::getCurrentLanguage())) {
     $langs = array_unique(array($lang, $cfg->getPrimaryLanguage()));