Drop benchmarks from Travis

[hdevalence]

They take a lot longer to run now.

[tarcieri]

If you marked them as allow_failures in matrix, you could also add fast_finish: true to matrix and they would continue to run, but not block merges.

[hdevalence]

That's a good suggestion. I'm not sure it makes sense to run benchmarks on Travis anyways, since there's no control over what the hardware is doing, so I'm not sure how meaningful it is. @isislovecruft ?

[tarcieri]

Yeah I have generally stopped benchmarking on Travis because the results have way too much variability for me to care

[isislovecruft]

Sounds good to me, I've never look at the Travis bench results because they don't mean much.