Wrong assertions in state specs

Throw assertions are written in an ambiguous way so compiler actually creates a wrapper function around method calls which renders the assertions useless, e.g.

``` coffeescript
-> participant.update_state().should.throw Error
```

becomes  

``` javascript
function() {
        return participant.update_state().should["throw"](Error);
};
```

which is not quite what's expected :confused: 
