adds: DateTime.to_unix can accept non-UTC DateTime structs
adds: DateTime.to_unix can accept non-UTC DateTime structs

ggcampinho/elixir,gfvcastro/elixir,lexmag/elixir,elixir-lang/elixir,antipax/elixir,ggcampinho/elixir,gfvcastro/elixir,kimshrier/elixir,kelvinst/elixir,beedub/elixir,kimshrier/elixir,pedrosnk/elixir,joshprice/elixir,kelvinst/elixir,pedrosnk/elixir,michalmuskala/elixir,beedub/elixir,antipax/elixir,lexmag/elixir