ConfigFile#ssl_ca_cert can now be set

This means we don't need to alter the configuration file at runtime to
set this.
Test configuring HTTPS connections in Request

This tests only that the correct certificates are added.  These basic
tests will allow #795 to be tested without adding network requests.
configured ca cert file is in addition to default ca certs
Test #795 without network access

This test makes sure both the ssl_ca_cert and the default certificates
get added to the certificate store.
Add #795 to History