DOC: setuptools is a required runtime dependency
Without setuptools pandas fails to import at https://github.com/pydata/pandas/blob/master/pandas/io/gbq.py#L9

hmm I think easier to simply eliminate the need for pkg_resources - not sure why this is in their in the first place 
 cc @jacobschaer 

can u just do gflags.**version** (or similar)?
 cc @jacobschaer ?
 @jreback I seem to recall Google was doing something weird with their version strings before. I'd have to look to see if that's still the case. Isn't setuptools a requirement for pandas anyways? @sean-schaefer
 @jacobschaer `setuptools` is only a requirement of building from source. not a run-time (on windows). 

Any way to eliminate its usage (e.g. using LooseVersion)?
 @jacobschaer ?
 Was looking into this - I'm having some account issues with GBQ for integration testing, but it looks like using:

```
if LooseVersion(apiclient.__version__ >= '1.2.0'):
```

works. However, that's only part of the `google-api-python-client` package. As for gflags, a quick look shows no easy way to identify it's version programatically. However, in light of https://github.com/pydata/pandas/issues/8327, it may no longer be needed...
 @jacobschaer 

I don't mind that setup tools is require for gbq
just don't want it necessary on main importing of pandas
can u move this detection so that it would fail w/ o setuptools ?
and then add setuptools to install.rst
 @jacobschaer status?
 During testing, I exceed a rate limiter in BQ (my bad - had two tests running at once on accident). I'll re-run the integration test later. I haven't tried removing setuptools from the virtual enviroment, but I can't see why this wouldn't work.  https://github.com/pydata/pandas/pull/8409
 Integration test finally passed locally. Still need to validate that it actually solved the problem... anyone want to try it? :D
 closing in favor of #8409 
