Fix #54.

Oddly, this is something we were already testing for, and the
tests worked. But in a different context it generated an error.
You have entered the twilight zone...(creepy music)

src/plain.jl

@@ -1020,6 +1020,7 @@ function read{S<:ByteString}(obj::DatasetOrAttribute, ::Type{Array{S}})
  close(objtype)
  end
  memtype_id = h5t_copy(H5T_C_S1)
+ h5t_set_cset(memtype_id, cset(S))
  if isempty(sz)
  ret = Array(S, 0)
  else