Update users.php so that getUser work

$this->checkRateLimit('users', 'show'); does not match a resource returned from Twitter. The correct resource to lookup is $this->checkRateLimit('users', 'show/:id');
Update to show the correct way to set the token
update test to use current rate response example from twitter api documentation
Merge pull request #3 from davidjosephhayes/master

Minor Updates