Fix currency symbol encoding in invoice PDF (#839)

css/invoice_email.css

@@ -38,6 +38,7 @@ pre { font-family: Helvetica; font-size: 13px; }
 #items { width: 100%;  border: 1px solid black; }
 #items th { background: #eee; }
 #items tr.item-row td { border: 0; vertical-align: top; }
+#items td { font-family: DejaVu Sans; }
 #items td.description { width: 300px; }
 #items td.item-name { width: 175px; }
 #items td.total-line { text-align: right; border-width: 1px 0 1px 1px; border-style: solid; }