double encoded signature

[dprize]

On line 28 of Oauth.js signature is being encoded twice.

 var getSignature = function(tokenSecret){
   return encode(consumerSecret) + "&" + encode(tokenSecret)
 }
 var signature = encode(getSignature(secret))

Changing it to the following solves the problem of not being able to receive an oauth token.

 var signature = getSignature(secret)