Add wgetpaste/wgetpaste.conf

Also add link in .hardlinks
Update .hardlinks

Add warning message that `check-hardlinks -f` should not always be done
blindly (e.g. `git config --global blah.blah blah` breaks the
git/gitconfig <-> ~/.gitconfig link, but the reference to use in this
case is the updated ~/.gitconfig, not the repo's git/gitconfig).
Update vim/vimrc

Add configuration for gist-vim.
Update git/gitconfig

Add github.user key for use with gist-vim.