Fix some lgtm alerts
Hi,
I just wanted to quickly fix a few alerts flagged up by lgtm.com. These are mostly simple ones but they were a few misnamed arguments in some calls. 

A total of 209 alerts have been found by lgtm.com, you can enable PR integration for automated PR reviews and flag these in the future before they find their way to the code base.
https://lgtm.com/projects/g/pydata/pandas/

I'm a big fan of pandas, I hope you'll find these useful!

 - [ ] closes #xxxx
 - [ ] tests added / passed
 - [x] passes ``git diff upstream/master --name-only -- '*.py' | flake8 --diff``
 - [ ] whatsnew entry