radsecproxy doesn't support TLSv1.1 or TLSv1.2

When initiating SSL context, tlscommon.c has the following code:

> ctx = SSL_CTX_new(TLSv1_method());
> ...
> ctx = SSL_CTX_new(DTLSv1_method());

This makes OpenSSL negotiate TLSv1 but not TLSv1.1 or TLSv1.2.