[WIP] Support multiple @find-by annotations

Still open tasks but basic support for multiple ```@find-by```. Still requiring some new unit tests and ```ElementCollection``` see #48 for more details.

Closes #13
Please transform 
```php
$selectors = (array)$selectors;

$annotations = array();
```
into
```php
$annotations = array();
$selectors = (array)$selectors;
```