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/doxygen/input/doc_x509.h

@@ -0,0 +1,45 @@
+/**
+ * \file doc_x509.h
+ *
+ * \brief X.509 module documentation file.
+ */
+/*
+ *
+ *  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)
+ */
+
+/**
+ * @addtogroup x509_module X.509 module
+ *
+ * The X.509 module provides X.509 support for reading, writing and verification
+ * of certificates.
+ * In summary:
+ *   - X.509 certificate (CRT) reading (see \c mbedtls_x509_crt_parse(),
+ *     \c mbedtls_x509_crt_parse_der(), \c mbedtls_x509_crt_parse_file()).
+ *   - X.509 certificate revocation list (CRL) reading (see
+ *     \c mbedtls_x509_crl_parse(), \c mbedtls_x509_crl_parse_der(),
+ *     and \c mbedtls_x509_crl_parse_file()).
+ *   - X.509 certificate signature verification (see \c
+ *     mbedtls_x509_crt_verify() and \c mbedtls_x509_crt_verify_with_profile().
+ *   - X.509 certificate writing and certificate request writing (see
+ *     \c mbedtls_x509write_crt_der() and \c mbedtls_x509write_csr_der()).
+ *
+ * This module can be used to build a certificate authority (CA) chain and
+ * verify its signature. It is also used to generate Certificate Signing
+ * Requests and X.509 certificates just as a CA would do.
+ */