Merge pull request #101 from jennybc/2013-05-nescent

Creating subdirectories. Adding a PDF of slides.
Updated git instructions for getting remote branch
Merge branch '2013-05-nescent' of github.com:swcarpentry/boot-camps into 2013-05-nescent
Adding Makefile and updated scripts for use with Make.
Creating a gitignore file with some entries good for R/RStudio projects.