TST: yahoo options tests additional skipping criteria

[jreback]

https://travis-ci.org/pydata/pandas/jobs/40415856
https://travis-ci.org/pydata/pandas/jobs/40425986
cc @dstephens99

These are hitting a ValueError on multiple-pr's I have seen. Maybe they are getting partial data?
So need to skip on that particular error (not exactly sure where that is coming from).

[jreback]

https://travis-ci.org/pydata/pandas/jobs/40606019

any thoughts on this?

[davidastephens]

Must be bad data from Yahoo. I'll send a pull request that checks to make sure it got a dataframe with size > 0 when it pulls from Yahoo.