Add/update recipes to build gtk through matplotlib dependencies
Use files in /proj/sot/ska/pkgs for gtk source deps
Remove gdk_pixbuf from matplotlib recipe
Switch cairo package to a gz from an xz
Add libpng 1.2.5 as libpng12
Add gtk+ as gtk_plus (was gtk-plus)
Merge pull request #36 from sot/conda_add_gtk

Add/update recipes to build gtk through matplotlib dependencies