BUG: Fixes #9281: fixes to tseries.tests.test_tslib.TestTimestamp
closes #9281 

The last test of both test_now and test_today was passing for anyone with a timezone
of UTC-5 or greater (but failed, for example, in US/Pacific).  The test was not
testing what the original author meant it to (which is that the times are very close
together) so I added abs(.) around the Timedeltas and also fixed the errant test.

thanks!
 I don't think abs() is necessary here given the order that the times are created so the difference will always be positive.  Nevertheless, thanks for fixing.
 @rockg, yeah, I wasn't too sure about the `abs`, but I was thinking it makes the tests more likely to catch some problematic code that someone writes in the future.  For example, take

```
self.assertTrue(abs(ts_from_method_tz - ts_from_string_tz) < delta)
```

If someone ends up rewriting `Timestamp.now(tz='US/Eastern')` and it erronesously causes `ts_from_string_tz` to have a value corresponding to the user's local time instead of US/Eastern, then because of `abs`, the test will fail not only for users with a timezone less than UTC-5, but rather for everyone.
