Remove write times from benchmarks

[yocontra]

The current benchmarks include not only the speed of the watch, but grunt.file.write times (and the 100ms delay) as well. I think the benchmark should really be testing the avg time to pick up a change event from the fs, right?

Working on some new benchmarks, PR inbound

[shama]

The benchmarks have fallen way behind here, #33. Updating to focus on fs events sounds like a better idea.

[shama]

Benchmarks are now easier to write and run: https://github.com/shama/gaze/tree/master/benchmarks