CbReport validation, report ids & ints

feed.py", line 175, in validate() has the following line:

```
    if not re.match("^[a-zA-Z0-9-_.]+$", self.data["id"]):
```

The use of regex presumes the report id field is a string.  If it's an int, this line blows up with an obscure error. 

Validation should either (a) exception on int report ids or (b) coerce ints to strings.
