Add initial mbedTLS and HTTPS example project (using howsmyssl.com JSON API)

mbedTLS version 2.1.0 (current stable)

Has some known issues/hacks:
* Entropy source not hooked in at all
* Linker script has a messy hack in it to store some (not all) data in
  irom

extras/mbedtls/component.mk

@@ -0,0 +1,56 @@
+# Component makefile for mbedtls
+
+# mbedtls by default builds into 3 libraries not one. We just use one for now (doesn't make a huge difference when static linking)
+
+# Config:
+# We supply our own hand tweaked mbedtls/config.h in our 'include' dir, the rest of upstream mbedtls is not changed.
+
+MBEDTLS_DIR = $(mbedtls_ROOT)mbedtls/
+INC_DIRS += $(mbedtls_ROOT)include $(MBEDTLS_DIR)include
+
+# these OBJS_xxx variables  are copied directly from mbedtls/mbedtls/Makefile,
+# minus a few values (noted in comments)
+#
+# If updating to a future mbedtls version you can just copy these in.
+OBJS_CRYPTO=	aes.o		aesni.o		arc4.o		\
+		asn1parse.o	asn1write.o	base64.o	\
+		bignum.o	blowfish.o	camellia.o	\
+		ccm.o		cipher.o	cipher_wrap.o	\
+		ctr_drbg.o	des.o		dhm.o		\
+		ecdh.o		ecdsa.o		ecp.o		\
+		ecp_curves.o	entropy.o	entropy_poll.o	\
+		error.o		gcm.o		havege.o	\
+		hmac_drbg.o	md.o		md2.o		\
+		md4.o		md5.o		md_wrap.o	\
+		memory_buffer_alloc.o		oid.o		\
+		padlock.o	pem.o		pk.o		\
+		pk_wrap.o	pkcs12.o	pkcs5.o		\
+		pkparse.o	pkwrite.o	platform.o	\
+		ripemd160.o	rsa.o		sha1.o		\
+		sha256.o	sha512.o	threading.o	\
+		timing.o	version.o			\
+		version_features.o		xtea.o
+# minus net.o
+
+OBJS_X509=	certs.o		pkcs11.o	x509.o		\
+		x509_create.o	x509_crl.o	x509_crt.o	\
+		x509_csr.o	x509write_crt.o	x509write_csr.o
+
+OBJS_TLS=	debug.o				ssl_cache.o	\
+		ssl_ciphersuites.o		ssl_cli.o	\
+		ssl_cookie.o	ssl_srv.o	ssl_ticket.o	\
+		ssl_tls.o
+
+# args for passing into compile rule generation
+mbedtls_INC_DIR =
+mbedtls_SRC_DIR = $(mbedtls_ROOT)
+mbedtls_EXTRA_SRC_FILES = $(patsubst %.o,$(MBEDTLS_DIR)library/%.c,$(OBJS_CRYPTO) $(OBJS_X509) $(OBJS_TLS))
+
+# depending on cipher configuration, some mbedTLS variables are unused
+mbedtls_CFLAGS = -Wno-error=unused-but-set-variable -Wno-error=unused-variable $(CFLAGS) 
+
+$(eval $(call component_compile_rules,mbedtls))
+
+# Helpful error if git submodule not initialised
+$(MBEDTLS_DIR):
+	$(error "mbedtls git submodule not installed. Please run 'git submodule update --init'")