Flashes won't clear when using store other than default CookieStore

[lufinima]

I've already seen older issues about this case when using Redis backed store #911 and supposedly it has been fixed with PR #1141 but it seem's there is an reversion because the bug is still around.
The fix in the PR if applied to current code seem's to fix the issue.
If the code

defer c.Flash().persist(c.Session())

line in the route_info.go is removed and added after route_info.go as

c.Flash().persist(c.Session())

, without the

defer

it works.
I've tested this fix with

FilesystemStore

and with a custom

SQLiteStore

[paganotoni]

This one is solved by v0.16.16