CS: PHP keywords MUST be in lower case

@localheinz That is `true` (pun intended :smile:)

Some tests:
```php
<?php

use \PHPUnit_Framework_TestCase;

define('AND', 'foo');
define('OR', 'bar');

class OperatorsTest extends PHPUnit_Framework_TestCase
{
    public function testOperatorHasPrecedenceOverConstant()
    {
        $this->assertFalse(false AND false);
        $this->assertFalse(false AND true);
        $this->assertFalse(true AND false);
        $this->assertTrue(true AND true);

        $this->assertFalse(false OR false);
        $this->assertTrue(false OR true);
        $this->assertTrue(true OR false);
        $this->assertTrue(true OR true);
    }

    public function testUndefinedVariableTriggersParseError()
    {
        $foo = true;
        $bar = false;

        // Parse error: syntax error, unexpected '$and' (T_VARIABLE) in ...
        $this->assertFalse($foo $and $bar);

        // Parse error: syntax error, unexpected '$or' (T_VARIABLE) in ...
        $this->assertTrue($foo $or $bar);
    }

    public function testBitwiseOrReturnsSameResultsAsRegularOperators()
    {
        $foo = true;
        $bar = false;

        // Failed asserting that 0 is false
        $this->assertFalse($foo & $bar);
        $this->assertFalse($foo && $bar);

        // Failed asserting that 1 is true
        $this->assertTrue($foo | $bar);
        $this->assertTrue($foo || $bar);
    }
}
```