Path to plugins directory about tgm-plugin-activation

[GaryJones]

Following on from this, rather than developers having to set the same path to each of the local zip files, you could introduce a default_path() API method that sets up a prefix for the theme, with their usage being:

TGM_Plugin_Activation::instance->default_path( 'path/to/my/theme/plugins/' );

Inside your class you would have something like:

class TGM_Plugin_Activation {

    protected $default_path = '';

    public function default_path( $path ) {
        $this->default_path = trailingslashit( $path );
    }

    public function tgm_do_plugin_install() {
        //...
        $source = $this->default_path . $instance['source'];
        //...
    }
}

If they don't set it, then there's no prefix (well, an empty string), and if they do, then it saves them having to repeat the same path everytime.