CS: PHP keywords MUST be in lower case

`and` and `or` operators are not same of `&&` and `||` as that they operate at different precedences.

```php
$foo = true;
$bar = false;
$baz = $foo and $bar;

var_dump($baz); // bool(true)
```
It results in `true` but if you use `&&` instead of `and` it would result in `false` :smile: because `=` has a higher precedence than `and`.
So I'd suggest you to always use `&&` and `||` in order to avoid bugs :D