storage: log vshard version during configuration

Users usually come to developers with logs, this logs has Tarantool's
version in it, but vshard version is missing there. Let's log version,
so that developers don't have to always ask users, which vshard version
is used there.

Closes #612

NO_DOC=internal
NO_TEST=minor

Author: Serpentian

vshard/storage/init.lua

@@ -3723,11 +3723,8 @@ local function storage_cfg_xc(cfgctx)
     local instance_id = cfgctx.instance_id
     local replicaset_id = cfgctx.replicaset_id
     local new_cfg = cfgctx.new_cfg
-    if M.replicasets then
-        log.info("Starting reconfiguration of replica %s", instance_id)
-    else
-        log.info("Starting configuration of replica %s", instance_id)
-    end
+    log.info('Starting %sconfiguration of replica %s at VShard %s',
+             M.replicasets and 're' or '', instance_id, consts.VERSION)
     if cfgctx.new_cfg.box_cfg_mode == 'manual' then
         if type(box.cfg) == 'function' then
             local msg = "Box must be configured, when box_cfg_mode is 'manual'"