MXS-2119: Fix file permissions

The admin files are now created with 640 permissions and automatically
created directories now properly set the permissions for the group as
well. All files and directories created by avrorouter and binlogrouter
also now correctly limit the read and write permissions only to the owner
and the group.

server/modules/routing/avrorouter/avro.c

@@ -1274,7 +1274,7 @@ static bool ensure_dir_ok(const char* path, int mode)
         if (rp)
         {
             /** Make sure the directory exists */
-            if (mkdir(rp, 0774) == 0 || errno == EEXIST)
+            if (mkdir(rp, 0770) == 0 || errno == EEXIST)
             {
                 if (access(rp, mode) == 0)
                 {