Update to Twitter API v1.1 endpoint.

It seems this will suffice.

Tested with: 

```lisp 
PLANETWIT> (post-to-twitter (list :guid "Testing API v1.1"
				  :title "It WORKS!"))
post-to-twitter: (:GUID "Testing API v1.1" :TITLE "It WORKS!")
posting "It WORKS! Testing API v1.1"
NIL
```
https://twitter.com/jsmp_api/status/347861102157238272