display correct primary user id in import dialogue MOSTLY

This is an incomplete fix; due to use of machine readable output, there
is no way to know the primary user id for keys fetched from a key
server.

Pending https://bitbucket.org/skskeyserver/sks-keyserver/issue/28/primary-uid-in-machine-readable-index

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/util/HkpKeyServer.java

@@ -294,6 +294,7 @@ public class HkpKeyServer extends KeyServer {
                 userIds.add(tmp);
             }
             entry.setUserIds(userIds);
+            entry.setPrimaryUserId(userIds.get(0));
 
             results.add(entry);
         }