re6stnet: fix PATH of registry service

supervisord unsets PATH and execvp falls back on the default value
  /bin:/usr/bin

software/re6stnet/software.cfg

@@ -39,8 +39,9 @@ eggs =
   re6stnet
 initialization =
   import os
-  path = os.environ.get('PATH', '')
-  os.environ['PATH'] = '${git:location}/bin' + (path and ':' + path)
+  path = os.environ.get('PATH', '/bin:/usr/bin')
+  os.environ['PATH'] = '${openssl:location}/bin:${git:location}/bin' + (
+    path and ':' + path)
 depends = ${re6stnet-develop:recipe}
 
 [re6stnet-backup]