Use internal reprojection if pyproj is unavailable, other steps toward generalization

I've made a few changes to get the code running on my machine, the first was to remove pyproj as a strict dependency by conditionally importing it, and writing some code to do the same operation using arcpy methods if it isn't available. This is one less package which will need to be installed by users, though it looks like pyproj does provide Python 2.7 packages that work with my copy of ArcGIS fine.

I've also made some other small changes: fixed tabs v. spaces, and relocated the layer files into a subdirectory, referencing them via local paths instead of a hard-coded one.