Merge pull request #2 from hansroland/master

PrettyPrint undefined values as" nn bytes undefined data"
fix bug when reading undefined tags where i would forget the last byte, also add pretty printer for user comment. change the pretty printer to return Text instead of String because for at least user comment we need encoding conversion. API break, so move to 0.6.0.0
fix aperture pretty printing
hlint run
split some functions to a new helpers module, parse gps date+time, nicely pretty print them and altitude too
oops that was not building
nicer pretty print for brightness
Added: Pretty Printer for the tag FileSource