FutureWarning about set_index (in_place=True) is raised even if you already fixed that
Pandas 0.10.1.
  It's throwing a FutureWarning "set_index with inplace=True will return None from pandas 0.11 onward" when I call set_index, **_even though I already changed my code to be compliant with that change so the warning is not relevant**_. It prints that warning anytime you call the function with inplace=True even if you are not using the return value. As it stands, the warning is largely useless -- if I call set_index in 20 places and I fixed 19 of them to not use the return code but missed the last one; then the warning is thrown on the first call (which I fixed) but not on the 20th call (which I didn't fix), so it doesn't help anyone find places to fix in their code. 

This warning is "harmless" in the sense it doesn't crash my code; but it is harmful in the sense that it clutters my error/warning log and therefore causing false positives in our infrastructure to notify us on job warnings/errors.

  Ideally, pandas should only print the warning if its relevant to you (IE, you haven't yet fixed your code) but I realize that's hard. If that's not possible, then can we have some sort of global option to disable that warning? 
