'bind' and 'bindAll'

Adds in support for 'bind' and 'bindAll', although 'bindAll' is not as fancy as it is in underscore.js. It needs to be used with the list construct.

Ex:

```php
<?php
require('underscore.php');

$f = function($passed=null) {
    echo $passed . "\n";
};

$f2 = function($passed=null) {
    var_dump($this);
};

$f =  __::bind($f, json_decode('{"property":"value"}'), 'passed by __', $f);
$f2 = __::bind($f2, json_decode('{"property":"value"}'), 'passed', $f);

$f('i passed this directly');
$f();
$f2();
$a = json_decode('{"property":"value"}');

$f = function() {
    $this->property = 'nope';
};

$f2 = function($passed=null) {
    var_dump($this);
};

list($f, $f2) = __::bindAll($a, $f, $f2);

$f();
$f2();
var_dump($a);
```