Support special objectAssertion templates for specific property types

For example, I would like custom assertions for BigDecimal only like: `has${Property}Of(Number value)`

```
public ${self_type} has${Property}Of(Number n) ${throws}{
if (new BigDecimal(n.toString()).compareTo(actual.${property}) != 0) {
throw new AssertionError("expected " + n + " but got " + actual.${property});
}
}
```
So then I can do:
```
PersonAssert.hasHeightOf(5);
```
Instead of
```
PersonAssert.hasHeightOf(BigDecimal.valueOf(5));
```

And of course I wouldn't want it to also generate `PersonAssert.hasNameOf(Number n);`.

So it would be nice to be able to specify a template just for BigDecimal property types. And I assume that this could be generalized to any property type.