Develop

These changes are a superset of pull request #2.  In addition to the files and dirs in #2, it adds the generated jam files project-config.jam and user-config.jam.  Also, the ignored files and dirs are prefixed with a / so that those same files and dirs won't accidentally match something in a subdir of the boost repo.

In addition to the generated files and dirs in boost, there are generated files and dirs in tools/build.  I placed a .gitignore file in that repos to ignore the appropriate files and dirs.  That is change is in a pull request for the build.git repo.

I also noticed changes were made to libs/system and tools/litre didn't have corresponding submodule refs in the boost repo.  In addition, added a submodule ref to the boost repo for my changes in tools/build.