[API REVIEW FOLLOWUP] SSL support extensions

[Susan Hinrichs]

I've updated my branch 
(https://github.com/shinrich/trafficserver/tree/ts-3006) and 
documentation (http://network-geographics.com/ats/docs/ssl-api.en.html) 
based on feed back from James a couple weeks back.

I took all of James' recommendations with two exceptions.
Instead of

tsapi TSReturnCode TSVConnTunnelToAddr(TSVConn, const struct sockaddr *);

I implemented

tsapi TSReturnCode TSVConnTunnel(TSVConn);

It looks like the current API uses a separate call to change the origin server 
address, e.g.

  tsapi TSReturnCode TSHttpTxnServerAddrSet(TSHttpTxn txnp, struct sockaddr 
const* addr);

Of course that exact call would not work in the SSL case because we don't have 
a TSHttpTxn object, but perhaps we could eventually add a similar function like 
TSVConnServerAddrSet(TSVConn, struct sockaddr *)?
 
Instead of

tsapi void TSVConnReenable(TSVConn, TSEvent);

I implemented

tsapi void TSVConnReenable(TSVConn);

It was not clear to me, where the event parameter should be sent.