Updating tags for HyperDualNumbers and Stan.

HyperDualNumbers is added with too low a tag when Pkg.add("HyperDualNumbers") is used. This started after moving it to JuliaDiff.

Stan I'm trying to update to get Travis to work and updates to the package reflecting Stan's update to 2.4.0.
I've also dropped DataFrames in favor of using a Dict for the simulation results for compatibility with Mamba and MCMC.