Standardize file extraction logic

[brendanorourke]

As it stands, logic to extract compressed files from HTTP downloads is all over the place, see here.

That's one ugly function.

Logic for extracting files should be abstracted into a util function, which can also be exposed as terminal bin, for the user.

A great example from nparikh:

smartextract () {
    if [ -f $1 ]; then
        case $1 in
            *.tar.bz2)  tar -jxvf $1        ;;
            *.tar.gz)   tar -zxvf $1        ;;
            *.bz2)      bunzip2 $1          ;;
            *.dmg)      hdiutil mount $1    ;;
            *.gz)       gunzip $1           ;;
            *.tar)      tar -xvf $1         ;;
            *.tbz2)     tar -jxvf $1        ;;
            *.tgz)      tar -zxvf $1        ;;
            *.zip)      unzip $1            ;;
            *.Z)        uncompress $1       ;;
            *)          echo "'$1' cannot be extracted/mounted via smartextract()" ;;
        esac
    else
        echo "'$1' is not a valid file"
    fi
}

[brendanorourke]

Note: some checks for installation of the appropriate tools (tar, gunzip, etc.) will be required, given that this repo spans both macOS and Ubuntu.

Or they can simply all be installed on init, or both-- :see_no_evil: