Change README.md: Add Compatibility section

I added a compatibility so users can know whether or not the install
script will support there OS.
Change vimrc: Add formatoptions

I added some formating options as well as a text width (72) to my vimrc.
Change vimrc: add autocmd to add t option to formatoptions in some files

I added an autocmd that adds the 't' options (automatic text-wrapping)
in some files (*.md, *.markdown, *.txt).