[core] Upgrade CherryPy that adds TLS certificate chain support

The version of CherryPy bundled with Hue does not support TLS certificate chain. The Hue will not hand out any intermediate certificates in response to TLS requests and this prevents effective use of PKI.

Fixing this will require an upgrade of CherryPy to a version that supports certificate chains and CA bundles and addition of config parameters to define the location of the CA bundle.

Note: some custom modifications were not backported to upstream CherryPy