Update AUTHORS

Catch a potential OSError when getting EXIF info

_getexif is pretty touchy about errors happening. It was already wrapped
in a generous try/except which catches most issues. It looks like this
one is happening with the TIFF plugin (which is odd, since the image
does seem to be a JPEG - I guess PIL is just confused).

Oh well, just add another exception clause to the except;pass branch.

Fixes SmileyChris#151.

Fix Django <1.3 support

easy_thumbnails.conf.settings extended BaseSettings, which was
introduced in 1.3. Falling back to importing from Settings if
that doesn't exist should solve our problem.

Document the new aliases funcitonality