Remove the word middleware (#1067)

* Rename middleware to plugin

first pass; mostly used 'sed', few spots where I manually changed
text.

This still builds a coredns binary.

* fmt error

* Rename AddMiddleware to AddPlugin

* Readd AddMiddleware to remain backwards compat

plugin/chaos/setup.go

@@ -0,0 +1,55 @@
+package chaos
+
+import (
+	"github.com/coredns/coredns/core/dnsserver"
+	"github.com/coredns/coredns/plugin"
+
+	"github.com/mholt/caddy"
+)
+
+func init() {
+	caddy.RegisterPlugin("chaos", caddy.Plugin{
+		ServerType: "dns",
+		Action:     setup,
+	})
+
+}
+
+func setup(c *caddy.Controller) error {
+	version, authors, err := chaosParse(c)
+	if err != nil {
+		return plugin.Error("chaos", err)
+	}
+
+	dnsserver.GetConfig(c).AddPlugin(func(next plugin.Handler) plugin.Handler {
+		return Chaos{Next: next, Version: version, Authors: authors}
+	})
+
+	return nil
+}
+
+func chaosParse(c *caddy.Controller) (string, map[string]bool, error) {
+	// Set here so we pick up AppName and AppVersion that get set in coremain's init().
+	chaosVersion = caddy.AppName + "-" + caddy.AppVersion
+
+	version := ""
+	authors := make(map[string]bool)
+
+	for c.Next() {
+		args := c.RemainingArgs()
+		if len(args) == 0 {
+			return chaosVersion, nil, nil
+		}
+		if len(args) == 1 {
+			return args[0], nil, nil
+		}
+		version = args[0]
+		for _, a := range args[1:] {
+			authors[a] = true
+		}
+		return version, authors, nil
+	}
+	return version, authors, nil
+}
+
+var chaosVersion string