HTTP/2 Cipher Suite Support

Motivation:
The HTTP/2 specification places restrictions on the cipher suites that can be used. There is no central place to pull the ciphers that are allowed by the specification, supported by different java versions, and recommended by the community.

Modifications:
-HTTP/2 will have a security utility class to define supported ciphers
-netty-handler will be modified to support filtering the supplied list of ciphers to the supported ciphers for the current SSLEngine

Result:
-Netty provides unified support for HTTP/2 cipher lists and ciphers can be pruned by currently supported ciphers
I wouldn't mind changing the interface but the order matters for the things that are not sets.  The ciphers are listed in order of preference and also returned according to this order (ones that are not supported are removed though).