title: ‘tls’ is not a member of ‘asio::ssl::context’ C++ error
body: <p>I am trying to build this github repository: <a href="https://github.com/socketio/socket.io-client-cpp" rel="nofollow noreferrer">https://github.com/socketio/socket.io-client-cpp</a></p>
  <p>It is dependant on this repository <a href="https://github.com/zaphoyd/websocketpp" rel="nofollow noreferrer">https://github.com/zaphoyd/websocketpp</a></p>
  <p>I got a few downloads while trying to build both and solved most with downloading libboost-dev and a few other libraries but i got an error that i can't seem to solve:</p>
  <pre><code>/home/ktbm/socket.io-client-cpp/src/internal/sio_client_impl.cpp: In member function ‘sio::client_impl::context_ptr sio::client_impl::on_tls_init(websocketpp::connection_hdl)’:
  /home/ktbm/socket.io-client-cpp/src/internal/sio_client_impl.cpp:586:83: error: ‘tls’ is not a member of ‘asio::ssl::context’
           context_ptr ctx = context_ptr(new  asio::ssl::context(asio::ssl::context::tls));
                                                                                     ^~~
  CMakeFiles/sioclient_tls.dir/build.make:110: recipe for target 'CMakeFiles/sioclient_tls.dir/src/internal/sio_client_impl.cpp.o' failed
  make[2]: *** [CMakeFiles/sioclient_tls.dir/src/internal/sio_client_impl.cpp.o] Error 1
  CMakeFiles/Makefile2:67: recipe for target 'CMakeFiles/sioclient_tls.dir/all' failed
  make[1]: *** [CMakeFiles/sioclient_tls.dir/all] Error 2
  Makefile:129: recipe for target 'all' failed
  make: *** [all] Error 2
  </code></pre>
  <p>I haven't found anyone with a similar problem and i am not sure which library causes this issue, probably an old asio library but could also be a boost error</p>