SSL socket support with CC3200 WiFi

I have implemented an .sslConnect() variant in WiFiClient so far which seems to work.  I was able to hit www.ti.com:443 using .sslConnect() and read ~87KB.

Unfortunately I am having a lot of trouble with the server cert verification process; actually uploading a .DER root CA file just hangs at sl_FsWrite().  My patch for WiFi includes the scaffolding to support that in a later revision but the .sslRootCA() function just returns false for now.