add microsoft office mimetypes to the fixlist - bugfix for oc-357

lib/mimetypes.fixlist.php

@@ -10,5 +10,11 @@ return array(
 	'pl'=>'text/x-script.perl',
 	'py'=>'text/x-script.phyton',
 	'vcf' => 'text/vcard',
-	'vcard' => 'text/vcard'
+	'vcard' => 'text/vcard',
+	'doc'=>'application/msword',
+	'docx'=>'application/msword',
+	'xls'=>'application/msexcel',
+	'xlsx'=>'application/msexcel',
+	'ppt'=>'application/mspowerpoint',
+	'pptx'=>'application/mspowerpoint'
 );