Add a dependency check for Pandoc 1.17.2
Add a dependency check for Pandoc 1.17.2

Prevent users from accidentially building with something other than the tested Pandoc 1.17.2

We're seeing subtle issues between different build versions with Pandoc -- especially as it relates to the PDF build. Forcing everyone to depend on the same 3rd party tool takes a layer of confusion out of the picture.

cse-sim/cse,cse-sim/cse