Updated to version 0.6.6, but the single quotes are unfortunately still not being converted.
Can maybe some form of simple preg_replace() be used for this special case. I tried this method, but turns out I do not know regex well enough to attempt it.
I came up with :
//Encode Special Case ' to '
$tweet->text = preg_replace('/[&]\#39;/', '\'', $tweet->text);