add cipher list to options

Author: Stephen von Takach

README.md

@@ -30,7 +30,10 @@ class transport
     is_server = true
     callback_obj = self
     options = {
-
+      verify_peer: true,
+      private_key: '/file/path.pem',
+      cert_chain: '/file/path.crt',
+      ciphers: 'ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-RC4-SHA:ECDHE-RSA-AES128-SHA:AES128-GCM-SHA256:RC4:HIGH:!MD5:!aNULL:!EDH:!CAMELLIA:@STRENGTH' # (default)
     }
     @ssl_layer = RubyTls::SSL::Box.new(is_server, callback_obj, options)
   end

lib/ruby-tls/ssl.rb

@@ -273,7 +273,7 @@ def initialize(server, options = {})
                     set_certificate(options[:cert_chain]  || SSL::DEFAULT_CERT)
                 end
 
-                SSL.SSL_CTX_set_cipher_list(@ssl_ctx, CIPHERS)
+                SSL.SSL_CTX_set_cipher_list(@ssl_ctx, options[:ciphers] || CIPHERS)
 
                 if @is_server
                     SSL.SSL_CTX_sess_set_cache_size(@ssl_ctx, 128)