bashrc: Move json_diffable() into its own program
Git: Make *.json files _actually_ diffable :)

Use the binary recently created in this repository.

Thank you JSON::Diffable!
vimrc: Add keybinding for jsonlint

jsonlint is an npm module:

https://github.com/zaach/jsonlint
Git: Add 'attributes' file

Put in 'diff' directives for file types that are currently in gitconfg:

- *.json
- *.tar
- *.odt
- *.doc

Update gitconfig to point to ~/.gitattributes.

Didn't want to use ~/.config/git/attributes since lots of other programs
use that and installing dotfiles would be messy that way.
Vim: Update incorrect comment