BUG: (GH4626) Fix decoding based on a passed in non-default encoding in pd.read_stata
closes #4626

@jseabold can you give this a once over; I included your file as a test case, FYI

It appears to me that everything is encoded by the default `cp1252`, the 'encoding' parameter is merely to then decode the strings
 cc @PKEuS

pls take a look as well
 One comment. It's not a showstopper, but Stata doesn't support unicode. So really the only valid encodings for reading in data are 'ascii' and 'latin-1' or equivalent. Maybe worth a mention in the docs?
 so it's really not possible to actually encode the data (unless u somehow did it external to stata?, meaning u encoded the bytes themselves
 Yes, AFAIK, the user has no control over this. A great source of anguish to me lately whenever my data passes through Stata. The only extended characters supported are latin-1. Some info here (from third-party software): http://stattransfer.com/faq/encoding.html
 ok I'll put in a doc mention
