*: add code to serialize templates into go code

Add a small program to iterate over the templates directory and
generate a go map of name to file data. This is so we can compile
these templates into the dex binary instead of requiring files on
disk.

Also add a Makefile rule to do this automatically.

server/templates_default_gen.go

@@ -0,0 +1,79 @@
+// +build ignore
+
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os/exec"
+	"path/filepath"
+)
+
+// ignoreFile uses "git check-ignore" to determine if we should ignore a file.
+func ignoreFile(p string) (ok bool, err error) {
+	err = exec.Command("git", "check-ignore", p).Run()
+	if err == nil {
+		return true, nil
+	}
+	exitErr, ok := err.(*exec.ExitError)
+	if ok {
+		if sys := exitErr.Sys(); sys != nil {
+			e, ok := sys.(interface {
+				// Is the returned value something that returns an exit status?
+				ExitStatus() int
+			})
+			if ok && e.ExitStatus() == 1 {
+				return false, nil
+			}
+		}
+	}
+	return false, err
+}
+
+type fileData struct {
+	name string
+	data string
+}
+
+func main() {
+	dir, err := ioutil.ReadDir("web/templates")
+	if err != nil {
+		log.Fatal(err)
+	}
+	files := []fileData{}
+	for _, file := range dir {
+		p := filepath.Join("web/templates", file.Name())
+		ignore, err := ignoreFile(p)
+		if err != nil {
+			log.Fatal(err)
+		}
+		if ignore {
+			continue
+		}
+
+		data, err := ioutil.ReadFile(p)
+		if err != nil {
+			log.Fatal(err)
+		}
+		files = append(files, fileData{file.Name(), string(data)})
+	}
+
+	f := new(bytes.Buffer)
+
+	fmt.Fprintln(f, "// This file was generated by the makefile. Do not edit.")
+	fmt.Fprintln(f)
+	fmt.Fprintln(f, "package server")
+	fmt.Fprintln(f)
+	fmt.Fprintln(f, "// defaultTemplates is a key for file name to file data of the files in web/templates.")
+	fmt.Fprintln(f, "var defaultTemplates = map[string]string{")
+	for _, file := range files {
+		fmt.Fprintf(f, "\t%q: %q,\n", file.name, file.data)
+	}
+	fmt.Fprintln(f, "}")
+
+	if err := ioutil.WriteFile("server/templates_default.go", f.Bytes(), 0644); err != nil {
+		log.Fatal(err)
+	}
+}