added robert's install script
made some quality of life improvements to @rwcarlsen's initial work. existing directories are now checked for and approriate actions are taken. also moved a lot of repeated functionality into functions.
added a checkout statement to make sure you pull for the correct branch
Merge pull request #471 from gidden/integration

Installation Integration - fetch and build entire cyclus toolchain in one script.
Merge branch 'eps' of github.com:katyhuff/cyclus into eps-extract
added some clarity to extract source block
removed superfluous semicolon