Fixed incorrect characters

[jtucker2]

I found that a number of the exercises' instructions have characters that seem to have been wrongly decoded from their original UTF-8 meaning, using some other encoding, and then saved into the files. I've fixed all of the wrong characters I found but there could potentially be more.

I fixed them using iconv to convert the contents of the files from UTF-8 to Windows-1252 (which I guessed was the incorrectly used encoding at some point when the original data was collected) and then saved the correct characters back into the files, along with some manual changing.

Here is a better explanation of the issue https://stackoverflow.com/a/2477480