Better way to install wp-cli

Old Way To Change Installation Dir:

```bash
curl http://wp-cli.org/installer.sh > installer.sh
INSTALL_DIR='/usr/share/wp-cli' sudo bash installer.sh
```

Now Better way

```bash
curl http://wp-cli.org/installer.sh | sudo bash -s /usr/share/wp-cli
```

Just Add  Following  2 Lines On Installation Scripts

INSTALL_DIR=$1
VERSION=$2