Tutorial for DataFrames v0.19.0

Tutorial for DataFrames v0.19.0 introduces major changes in data frame indexing rules.
See https://github.com/JuliaData/DataFrames.jl/releases/tag/v0.19.0 for details.

Last release supporting Julia 0.6.4

After this release this tutorial will support Julia 1.0 only.

Tutorial version for DataFrames 0.11.6

DataFrames_0.11.6

add another way to extract row as a vector