Scala Common Enrich: support IPv6 addresses in the IpAddressExtractor

[miike]

Currently the IpAddressExtractor performs an extract using the following regular expression

^x-forwarded-for: ((?:[0-9]|\.)+).*

If an IPv6 address occurs in the leftmost position in the X-Forwarded-For header this will result in a concatenated IP address. This can be fixed by allowing the x-forwarded-for regular expression to match additional alphabetic and separator : characters.