Updated doc Directory

1. Updated tep.css to the recent version that was used in the html files
committed in the repository.
2. Fixed errors in the more recent teps that kept them from compiling.
3. Updated the build output to docutils 0.10.
4. Added html and pdf files for more recent TEPs.
5. Added .gitignore
6. Updated Makefile to build pdfs and track dependencies correctly.