Feature/ws cli (#15)

* New command line tool for transfering files / still very beta.

* add readme

* use cli11 for argument parsing

* json -> msgpack

* stop using base64 and use binary which can be stored in message pack

ws/ixcrypto/IXHMac.cpp

@@ -0,0 +1,27 @@
+/*
+ *  IXHMac.h
+ *  Author: Benjamin Sergeant
+ *  Copyright (c) 2018 Machine Zone. All rights reserved.
+ */
+#include "IXHMac.h"
+#include "IXBase64.h"
+
+#include <openssl/hmac.h>
+
+namespace ix
+{
+    std::string hmac(const std::string& data, const std::string& key)
+    {
+        constexpr size_t hashSize = 16;
+        unsigned char hash[hashSize];
+
+        HMAC(EVP_md5(),
+             key.c_str(), (int) key.size(),
+             (unsigned char *) data.c_str(), (int) data.size(),
+             (unsigned char *) hash, nullptr);
+
+        std::string hashString(reinterpret_cast<char*>(hash), hashSize);
+
+        return base64_encode(hashString, (uint32_t) hashString.size());
+    }
+}