Support delaying responses

go/fake-http/README.md

- support matching query strings
- refactoring
- /_clear endpoint
- (randomized) delays
- some kind of templating (request info + random functions?)
- lua integration? ;)

go/fake-http/fake-http.go

	"io"
	"io/ioutil"
	"log"
	"math/rand"
	"net/http"
	"net/url"
	"os"
	"os/exec"
	"path"
	"strings"
	"time"
	"gopkg.in/yaml.v2"
)
		resp = &Response{Status: 404, Body: "Not found"}
	}
	time.Sleep(resp.Delay)
	if resp.RandomDelay > 0 {
		time.Sleep(time.Duration(rand.Intn(int(resp.RandomDelay))))
	}
	for _, header := range resp.Headers {
		w.Header().Set(header.Name, header.Value)
	}
	Status  int      `yaml:"status"`
	Headers []Header `yaml:"headers"`
	Body    string   `yaml:"body"`
	Delay       time.Duration `yaml:"delay"`
	RandomDelay time.Duration `yaml:"randomDelay"`
}
func (resp Response) String() string {