replace knox git dependency with knox-s3 (#4574)

- knox-s3 is a fork of knox with one difference: a mime 1.x dependency that avoids breaking changes in mime 2.x
- this matches the `keystonejs/knox` repo, but is published to npm
- allows keystone to be installed without git e.g. in a node:slim Docker container

close #4573

admin/server/api/s3.js

@@ -5,7 +5,7 @@ TODO: Needs Review and Spec
 module.exports = {
 
 	upload: function (req, res) {
-		var knox = require('knox');
+		var knox = require('knox-s3');
 		var keystone = req.keystone;
 		var Types = keystone.Field.Types;
 

fields/types/s3file/S3FileType.js

@@ -68,7 +68,7 @@ Object.defineProperty(s3file.prototype, 's3config', {
  */
 s3file.prototype.addToSchema = function (schema) {
 
-	var knox = require('knox');
+	var knox = require('knox-s3');
 	var field = this;
 
 	var paths = this.paths = {
@@ -333,7 +333,7 @@ s3file.prototype.generateHeaders = function (item, file, callback) {
  */
 s3file.prototype.uploadFile = function (item, file, update, callback) {
 
-	var knox = require('knox');
+	var knox = require('knox-s3');
 	var field = this;
 	var path = field.options.s3path ? field.options.s3path + '/' : '';
 	var prefix = field.options.datePrefix ? moment().format(field.options.datePrefix) + '-' : '';

package.json

@@ -51,7 +51,7 @@
     "kerberos": "0.0.23",
     "keystone-storage-namefunctions": "1.1.1",
     "keystone-utils": "0.4.0",
-    "knox": "keystonejs/knox",
+    "knox-s3": "0.9.5",
     "less-middleware": "2.2.1",
     "letsencrypt-express": "2.0.6",
     "list-to-array": "1.1.0",