Updated config to include list of valid characters to `sess_cookie_name`

Added list of valid characters to sess_cookie_name
Update config.php

Removed new line
Merge pull request #2643 from brenjt/patch-1

Updated config to include list of valid characters to `sess_cookie_name`
[ci skip] Remove empty line at application/config/config.php EOF
No need of this anymore
No need of this anymore
Merge pull request #2644 from vkeranov/develop

No need of these comment lines anymore
[ci skip] Remove empty lines
Adding missing reference to min_length in rules reference