correct blacklist export as text url to blacklists_p.txt

was using servlet for network access and missing network.unit.name
fix for http://mantis.tokeek.de/view.php?id=694
+ prevent unresoved_pattern in yacy/list servlet

htroot/BlacklistImpExp_p.html

@@ -80,7 +80,7 @@
             </fieldset>
         </form>
 
-        <form action="yacy/list.html" method="get" accept-charset="UTF-8">
+        <form action="api/blacklists_p.txt" method="get" accept-charset="UTF-8">
             <fieldset>
                 <legend>plain text file:</legend>
                 Here you can export a blacklist as a regular text file with one blacklist entry per line.

htroot/api/blacklists_p.txt

@@ -0,0 +1,4 @@
+#{lists}#
+#{items}##[item]#
+#{/items}#
+#{/lists}#

htroot/yacy/list.java

@@ -51,6 +51,7 @@ public final class list {
 
         // return variable that accumulates replacements
         final serverObjects prop = new serverObjects();
+        prop.put("list", ""); // init a empty return (error case)
         if ((post == null) || (env == null)) return prop;
         if (!Protocol.authentifyRequest(post, env)) return prop;
 
@@ -66,7 +67,7 @@ public final class list {
 
         if ((sb.isRobinsonMode()) && (!sb.isInMyCluster(otherPeerName))) {
             // if we are a robinson cluster, answer only if this client is known by our network definition
-            return null;
+            return prop;
         }
 
         if (col.equals("black")) {
@@ -85,8 +86,6 @@ public final class list {
             }
 
             prop.put("list",out.toString());
-        } else {
-            prop.put("list","");
         }
 
         return prop;