Workaround for deprecated functions in julia-0.3-rc1

This is an workaround for #649
It would be best to test it, and also add tests for these to `test/show.jl`. My guess is that the note at https://github.com/JuliaStats/DataFrames.jl/blob/5441509a6e06df2c4c114275b79298e65172a3f2/src/dataframe/reshape.jl#L235 is no longer correct, and the `show` functions in Base now work just fine.