Add support for SNI on SSL connections

[kampka]

Connecting to SSL secured hosts that require SNI (Server Name Indication) support is currently not possible without accepting all certificates, which is of course undesirable. It would be nice if ZAX would support SNI so proper hostname based TLS negotiation can be performed.

I've done some research and found a couple of resources indicating that SNI is possible on Android.

http://source-android.frandroid.com/libcore/luni/src/main/java/libcore/net/http/HttpsURLConnectionImpl.java

http://source-android.frandroid.com/libcore/luni/src/main/java/libcore/net/http/HttpConnection.java

http://source-android.frandroid.com/libcore/luni/src/main/java/org/apache/harmony/xnet/provider/jsse/OpenSSLSocketImpl.java

There is an setHostname() method in OpenSSLSocketImpl that if called
causes NativeCrypto.SSL_set_tlsext_host_name() to be called. That in
turn calls SSL_set_tlsext_host_name().

Hopefully, this is helpful.