Feature/allocate

`allocate` now supports the following form: `$m->allocate(1, 1, 1)` (array can be ommited)

Adds `allocateTo`: Divides the amount to N equal values (the remainder is shared between the first K results)

Example:
``` php
$m = new Money::EUR(15);

// Returns [8, 7]
$m->allocateTo(2);
```

Please merge #55 before, so I can rebase this if needed
It does not mean you cannot use arrays. If it is mentioned in the docs you just go with it and don't use any other way. However, IMO using array is the same as using many parameters. At the end, they also become an array.