When you pass a string to R.test instead of a regex, it always returns true

The following code returns true:

``` javascript
R.test('foo', 'bar')
```

[Here it is in the repl](http://bit.ly/1Jz66KK).

This seems like a pretty easy mistake to make, and I think the appropriate behavior is to throw an exception and point out that the first argument is not the correct type.
