Add a debug/info task to list installed versions

[ocean90]

To quickly check the installed versions of PHP, WP-CLI and composer a deploy:debug or debug:remote task would be helpful.

task('deploy:debug', function () {
	writeln( '<info>WP-CLI info:</info>' );
	writeln( run( 'wp cli info' ) );
	writeln( '<info>PHP info:</info>' );
	writeln( run( 'php -v' ) );
	writeln( '<info>Composer info:</info>' );
	writeln( run( 'composer -V' ) );
} );

Note that deploy:info already exists.