Remove user-facing references to Observium

This eliminates nearly all of the user-facing references to Observium,
including in the names of temporary files and in the metadata of PDFs.  Many
of these may not be used any more, but I've adjusted them anyway.  These
changes should also make it easier to change the branding later if it is
needed.  There are a few references of which I still don't understand the
significance, so I've left them as-is for now.  The Unix agent in particular
is rather untidy.

includes/snmp.inc.php

@@ -92,8 +92,7 @@ function snmp_get($device, $oid, $options = NULL, $mib = NULL, $mibdir = NULL)
 
   if (strstr($oid,' '))
   {
-    echo("BUG: snmp_get called for multiple OIDs: $oid\n");
-    echo("Please report this to the Observium team.");
+    echo(report_this_text("snmp_get called for multiple OIDs: $oid"));
   }
 
   $cmd  = $config['snmpget'];
@@ -776,7 +775,8 @@ function snmp_gen_auth (&$device)
     if ($device['authlevel'] === "noAuthNoPriv")
     {
       // We have to provide a username anyway (see Net-SNMP doc)
-      $cmd .= " -u observium";
+      // FIXME: There are two other places this is set - why are they ignored here?
+      $cmd .= " -u root";
     }
     elseif ($device['authlevel'] === "authNoPriv")
     {