asv `goal_time` wrong attribute?
The pandas benchmarks use a parameter `goal_time = 0.2`, but looking at the asv [docs](https://asv.readthedocs.io/en/latest/writing_benchmarks.html) and at the asv code itself, I don't see "goal_time" anywhere.  Should this be `sample_time` instead?  From the docs:


    sample_time: asv will automatically select number so that each sample takes
    approximatively sample_time seconds. If not specified, sample_time defaults to 0.1 seconds.
