Merge pull request #319 from Desp4/master

Make non-cmake installation instructions mimic cmake

Author: jmigual

INSTALL.md

@@ -10,7 +10,8 @@
 1. Use `git clone --recurse-submodules https://github.com/socketio/socket.io-client-cpp.git` to clone your local repo.
 2. Add `./lib/asio/asio/include`, `./lib/websocketpp` and `./lib/rapidjson/include` to headers search path.
 3. Include all files under `./src` in your project, add `sio_client.cpp`,`sio_socket.cpp`,`internal/sio_client_impl.cpp`, `internal/sio_packet.cpp` to source list.
-4. Include `sio_client.h` in your client code where you want to use it.
+4. Add `BOOST_DATE_TIME_NO_LIB`, `BOOST_REGEX_NO_LIB`, `ASIO_STANDALONE`, `_WEBSOCKETPP_CPP11_STL_` and `_WEBSOCKETPP_CPP11_FUNCTIONAL_` to the preprocessor definitions
+5. Include `sio_client.h` in your client code where you want to use it.
 
 ### With vcpkg