Description:
------------
OAuth extension generates invalid SBS for requests with array params. This happens both with oauth_get_sbs and with OAuthProvider (although results differ).

For oauth_get_sbs() key names are lost when generating SBS. However when setting collapsed param name as string methods yelds correct results:

oauth_get_sbs("GET","http://host/path", [ "include[answers]" => 1  ]));

When using OAuthProvider (with live requests) param name gets encoded twice on the other hand. Also debug_sbs is truncated. I don't know if it's just debug output that is cut or the real base string.

Test script:
---------------
var_dump(
  oauth_get_sbs(
    "GET",
    "http://host/path", 
    [ "name" => [ "key" => "value" ]  ]
  )
);

// also data from real world example with OAuthProvider

Expected result:
----------------
string(57) "GET&http%3A%2F%2Fhost%2Fpath&include%255Banswers%255D%3D1"

// when OAuthProvider receives request (parts removed but same)
// this is from a client sending request (not a PHP Pecl extension)

GET&https%3A%2F%2F....&include%255Banswers%255D%3D1%26oauth_consumer_key....oauth_token%3D9f98c213db%26oauth_version%3D1.0

Actual result:
--------------
string(41) "GET&http%3A%2F%2Fhost%2Fpath&name%3Dvalue"

// when OAuthProvider receives request (parts removed but same)
// this is from debug_sbs returned through OAuthException

GET&https%3A%2F%2F....&include%3D1%26include%255Banswers%255D%3D1%26oauth_consumer_key....oauth_token%3D9f98c213db%26oauth_ver