* misc cleanups

you could also see more stable results by simply fetching the files in order instead of at random.


	[ `go version` | done: 36.064151ms ]
		go version go1.1 linux/amd64

old:

    [ `go test -test.run=none -test.bench="^Benchmark" -cpu 1,2,4 -benchmem` | done: 29.473057053s ]
        PASS
        BenchmarkOriginal       10000        110185 ns/op       14125 B/op         104 allocs/op
        BenchmarkOriginal-2      5000        631620 ns/op       14102 B/op         104 allocs/op
        BenchmarkOriginal-4      5000        646266 ns/op       14168 B/op         104 allocs/op
        BenchmarkCached         20000         85874 ns/op       12650 B/op          81 allocs/op
        BenchmarkCached-2       10000        517357 ns/op       12721 B/op          81 allocs/op
        BenchmarkCached-4        5000        548556 ns/op       12661 B/op          81 allocs/op
        BenchmarkMemfs          10000        146477 ns/op       46474 B/op          99 allocs/op
        BenchmarkMemfs-2         5000        640177 ns/op       46439 B/op          99 allocs/op
        BenchmarkMemfs-4         5000        645501 ns/op       46473 B/op          99 allocs/op
        ok      github.com/blaxill/static    28.618s

new:

    [ `go test -test.run=none -test.bench="^Benchmark" -cpu 1,2,4 -benchmem` | done: 28.090098332s ]
        PASS
        BenchmarkOriginal       20000         90427 ns/op        7871 B/op         100 allocs/op
        BenchmarkOriginal-2      5000        581354 ns/op        7870 B/op         100 allocs/op
        BenchmarkOriginal-4      5000        602386 ns/op        7870 B/op         100 allocs/op
        BenchmarkCached         50000         66744 ns/op        6486 B/op          77 allocs/op
        BenchmarkCached-2        5000        480580 ns/op        6486 B/op          77 allocs/op
        BenchmarkCached-4        5000        522957 ns/op        6486 B/op          77 allocs/op
        BenchmarkMemfs          10000        100038 ns/op       40277 B/op          95 allocs/op
        BenchmarkMemfs-2         5000        561501 ns/op       40280 B/op          95 allocs/op
        BenchmarkMemfs-4         5000        579472 ns/op       40275 B/op          95 allocs/op
        ok      github.com/blaxill/static    27.211s