Webtrends reports

Do not merge until we've talked about inconsistent id formatting:

This fixes the inconsistency between default ids formatting datetimes to 
```
20140519000000
```
and specifiying `_timestamp` as part of the `idMapping` which leaves things like this:
```
 "humanId": "2014-05-19 00:00:00+00:00weekstart", 
```