ring-jetty-adapter should expose `setExcludeCipherSuites`

[MIJOTHY-V2]

a91d874 added the ability to extend the list of excluded ciphers by calling out to SslContextFactory.addExcludeCipherSuites. However, this operation is purely additive. There are use-cases for replacing the set of excluded cipher suites, and SslContextFactory exposes this functionality through SslContextFactory.setExcludeCipherSuites.

The particular use-case I'm interested in is the running of jetty on IBM JVMs. Since the IBM JVM prefixes its cipher suites with SSL_, and ciphers matching this regex are considered naughty, jetty servers interacted with via ring-jetty-adapter are unable to run on https on IBM JVMs without severe hacks (think mutating via :configurator sort of hacks).

Since this functionality is exposed by jetty under the hood anyway, I reckon it wouldn't be a bad thing to expose it via ring-jetty-adapter. Something along the lines of :override-exclude-ciphers and override-exclude-protocols? Happy to PR.

Example jetty issues relating to the IBM thing:

• https://github.com/eclipse/jetty.project/issues/3817
• https://github.com/eclipse/jetty.project/issues/2921

[weavejester]

Those additional options seem fine to me.