Added the following two network-specific configuration options that can
be changed via controlpanel or webadmin:
* TrustAllCerts: Will trust ALL certificates when enabled, effectively
disabling TLS certificate validation.
Default value: false
* TrustPKI: Whether or not to trust PKI-valid certificates. Setting this
to false will make znc trust only trusted certificates added by the
user.
Default value: true
With default values, behavior is exactly the same as before.
This is based on the work of Roelf Wichertjes. See YourBNC/znc@5c747598.
See znc/znc#866.