Grep and ls use colors by default

I noticed that cash's grep uses colored output by default. This doesn't seem to be a POSIX compliant default, however. On my Ubuntu system, if I type `grep 'o' package.json`, it's true that I'll see colored output, but that's because Ubuntu aliases `grep` by default.

You can see the actual default behavior of GNU grep if you type something like:

``` Bash
bash $ \grep 'o' package.json # Putting a backslash in front makes sure bash doesn't call an alias
bash $ alias grep # see what it's aliased to
alias grep='grep --color=auto'
```

I'm not sure if cash's default was by design (which wouldn't be the worst decision), or if it was just assumed this was the default.

I noticed the same thing with `ls`, which also doesn't use colors by default, it just so happens that it's commonly aliased to `alias ls='ls --color=auto'`.