Allow specifying SSL context information for CAS authority

[rsutphin]

The CAS authority needs to communicate with CAS servers which are generally SSL-protected. Provide a mechanism where Aker's CAS authority can be configured with:

• An OpenSSL verify mode,
• An OpenSSL-compatible ca_file, an/or
• An OpenSSL-compatible ca_path

[hannahwhy]

Proposal:

Aker.configure do
  cas_parameters :ssl => { :verify_mode => OpenSSL::SSL::VERIFY_PEER, :ca_file => some_file }
  ...
 end

We could also do

Aker.configure do
  ssl_parameters :verify_mode => OpenSSL::SSL::VERIFY_PEER, :ca_file => some_file #, ...
  ...
end

and just let whatever authorities/modes need an SSL context use it, but that may be assuming too much about the uniformity of SSL deployments.

[rsutphin]

but that may be assuming too much about the uniformity of SSL deployments

I had the same thought — we'd want to make it overrideable per authority, so at best we'd need to support both. I say just do the cas_parameters one for now. If an app needs to share the parameters between two different authorities (or whatever), it can just do:

ssl_opts = { ... }
Aker.configure do
  cas_parameters :ssl => ssl_opts
  whatever_parameters :ssl_context => ssl_opts
end