Report Synthetic IPv6 Address for Bridge Distribution Intergration(merged with rebase)

This is a merge request implementing the Synthetic IPv6 Address support as discussed in #17 (closed).

The Synthetic IPv6 Address is generated by:

1. Encode ("WEBTUNNEL+" || WebtunnelBridgeURL) as utf8 and calculate its sha256 hash.
2. Bit select prefix number of bits from prefix CIDR and select rest of bits from hash as the Synthetic IPv6 Address.