Remove the ability to do tls 1.0 and 1.1 from libtls.

Remove the ability to do tls 1.0 and 1.1 from libtls.

With this change any requests from configurations to request
versions of tls before tls 1.2 will use tls 1.2. This prepares
us to deprecate tls 1.0 and tls 1.1 support from libssl.

ok tb@