need simple function for updating plugins

[ChristianChiarulli]

No description provided.

[Pheon-Dev]

What about creating a zap function and a --help flag to show zap options such as:

# From the CLI
$ zap update plugin_name
$ zap update all
$ zap delete plugin_name
$ zap pause plugin_name
$ zap source plugin_name
$ zap ...

Then have this added to the zap script

# zap function that takes one or two arguments 

function zap() {
  if [ -f $1 ]; then
    case $1 in
      update)    git pull https://github.com/$2    ;;
      delete)    rm -rf ~/.local/share/zap/plugins/$1    ;;
...
...
      *)            echo "'$1' cannot be found in zap plugins" ;;
    esac
  else
    echo "'$1' is not a valid plugin"
  fi
}

[Pheon-Dev]

Check #15