Ensure we're reading up-to CRLF (\r\n) for commands

In TLS, the socket is an `OpenSSL::SSLSocket`, calling `gets` will try
to read the buffer using the value of `$/` (`\n` on Linux/MacOS) as separator,
which seems to mess with the `BufferedIO`.

features/support/test_client.rb

@@ -213,7 +213,7 @@ def with_binary(*args, &block)
         if @override_with_binary
           block.call
         else
-          return orig_with_binary(*args, &block)
+          orig_with_binary(*args, &block)
         end
       end
 

lib/ftpd/command_loop.rb

@@ -8,6 +8,8 @@ class CommandLoop
 
     include Error
 
+    CRLF = "\r\n"
+
     def initialize(session)
       @session = session
     end
@@ -62,7 +64,7 @@ def gets_with_timeout(socket)
       socket = socket.to_io if @session.tls_enabled? && !socket.encrypted?
       ready = IO.select([socket], nil, nil, config.session_timeout)
       timeout if ready.nil?
-      ready[0].first.gets
+      ready[0].first.gets(CRLF)
     end
 
     def timeout