Provide host name to certificate_check_cb

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Add tests for host names

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Merge pull request #2574 from csware/hostname-for-certificate_check_cb

Provide host name to certificate_check_cb