Add HashiCorp Nomad provider (#483)

* provider: adding Nomad provider

* updating CONTRIBUTING.md with Nomad provider

* updated README.md by adding the Nomad provider

* fix typo

* adding nomad/api and nomad/testutil deps

* adding Nomad binary dependency for provider tests

* fixed the nomad binary download command step and added tolerations to the nomad provider.

* adding nomad provider demo gif

* adding my name to authors

* adding two missing go-rootcerts files after dep ensure

* delete pod comment

vendor/github.com/hashicorp/go-cleanhttp/handlers.go

@@ -0,0 +1,43 @@
+package cleanhttp
+
+import (
+	"net/http"
+	"strings"
+	"unicode"
+)
+
+// HandlerInput provides input options to cleanhttp's handlers
+type HandlerInput struct {
+	ErrStatus int
+}
+
+// PrintablePathCheckHandler is a middleware that ensures the request path
+// contains only printable runes.
+func PrintablePathCheckHandler(next http.Handler, input *HandlerInput) http.Handler {
+	// Nil-check on input to make it optional
+	if input == nil {
+		input = &HandlerInput{
+			ErrStatus: http.StatusBadRequest,
+		}
+	}
+
+	// Default to http.StatusBadRequest on error
+	if input.ErrStatus == 0 {
+		input.ErrStatus = http.StatusBadRequest
+	}
+
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// Check URL path for non-printable characters
+		idx := strings.IndexFunc(r.URL.Path, func(c rune) bool {
+			return !unicode.IsPrint(c)
+		})
+
+		if idx != -1 {
+			w.WriteHeader(input.ErrStatus)
+			return
+		}
+
+		next.ServeHTTP(w, r)
+		return
+	})
+}