[ruby] Enable ruby mode for Guardfiles
[appendix-b] First pass at describing how to build a central emacs config
[appendix-a] Stop extracting (aka tangling) certain blocks

These blocks are only meant for display purposes.
[general-setup] First draft of package management
[file organization] Eliminate component .el files

These are replaced by init.el. This new file also contains the
contents of appendix-b.org (which previously weren't present
anywhere).
[appendix-b] Code is now tangled out to init.el