Fix X-EVOLUTION-FILE-AS escape

Evolution defaults to the form "X-EVOLUTION-FILE-AS:Bloggs\, Joe", and
since Evolution uses this field as the contacts' displayed name, it's
highly visible when ownCloud turns it into
"X-EVOLUTION-FILE-AS:Bloggs\\, Joe".

#42 (comment)

When interacting with Evolution-Data-Server (which I think MeeGo might
use), the same incorrect escaping applies to X-EVOLUTION-FILE-AS. This
is a non-standard field, but it's highly visible for Evolution users,
since it's used as the default displayed name for contacts there.

owncloud/core#2335 (comment)

Bug-Debian: http://bugs.debian.org/735112

appinfo/app.php

@@ -15,6 +15,7 @@
 \Sabre\VObject\Property::$classMap['TEL']		= '\OC\VObject\StringProperty';
 \Sabre\VObject\Property::$classMap['IMPP']		= '\OC\VObject\StringProperty';
 \Sabre\VObject\Property::$classMap['URL']		= '\OC\VObject\StringProperty';
+\Sabre\VObject\Property::$classMap['X-EVOLUTION-FILE-AS'] = '\OC\VObject\StringProperty';
 \Sabre\VObject\Property::$classMap['N']			= '\OC\VObject\CompoundProperty';
 \Sabre\VObject\Property::$classMap['ADR']		= '\OC\VObject\CompoundProperty';
 \Sabre\VObject\Property::$classMap['GEO']		= '\OC\VObject\CompoundProperty';