Add support for json configuration files during rats-tls initialization

[YangLiang3]

rats-tls initialization will analyze the following paramters and set them in rats-tls. When verifying quote, it can verify sgx_mrs paramters(mr_enclave/mr_signer), according to verify_mr_enclave/verify_mr_signer's selection(on/off)
{
"LOG_LEVEL": "debug" // or "error"
"cert_algo": "ECC" // or RSA2408
"verify_mr_enclave": "on",
"verify_mr_signer": "on",
"verify_isv_prod_id": "on",
"verify_isv_svn": "on",
"sgx_mrs": [
{
"mr_enclave": "",
"mr_signer": "",
"isv_prod_id": "0",
"isv_svn": "0"
}
],
}