Feature/mbedtls (#84)

* try to import mbedtls and build it

* add stubs socket class

* some boilterplate, read and write function implemented

* more boilterplate / current error in handshake because no CA cert is setup

* add something so skip ca verification, can ws curl https://google.com !

* cleanup / close implemented

* tweak CMakefiles

* typo in include

* update readme

* disable unittests

third_party/mbedtls/scripts/data_files/version_features.fmt

@@ -0,0 +1,60 @@
+/*
+ *  Version feature information
+ *
+ *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *  This file is part of mbed TLS (https://tls.mbed.org)
+ */
+
+#if !defined(MBEDTLS_CONFIG_FILE)
+#include "mbedtls/config.h"
+#else
+#include MBEDTLS_CONFIG_FILE
+#endif
+
+#if defined(MBEDTLS_VERSION_C)
+
+#include "mbedtls/version.h"
+
+#include <string.h>
+
+static const char *features[] = {
+#if defined(MBEDTLS_VERSION_FEATURES)
+FEATURE_DEFINES
+#endif /* MBEDTLS_VERSION_FEATURES */
+    NULL
+};
+
+int mbedtls_version_check_feature( const char *feature )
+{
+    const char **idx = features;
+
+    if( *idx == NULL )
+        return( -2 );
+
+    if( feature == NULL )
+        return( -1 );
+
+    while( *idx != NULL )
+    {
+        if( !strcmp( *idx, feature ) )
+            return( 0 );
+        idx++;
+    }
+    return( -1 );
+}
+
+#endif /* MBEDTLS_VERSION_C */