Let npm pack create the assets tarball for us

That way the tarball we upload to Github is the same as the one that we
get from installing Converse via NPM.

CC @ChaosKid42

To create the tarball containing the assets, just run `npm pack`.
This is the same tarball that gets uploaded to https://npmjs.org

Makefile

@@ -99,22 +99,7 @@ release:
 	make po
 	make po2json
 	make build
-	mkdir -p 'converse-assets-$(VERSION)'
-	$(INSTALL) -D dist/converse.js 'converse-assets-$(VERSION)/converse.js'
-	$(INSTALL) -D dist/converse.min.js 'converse-assets-$(VERSION)/converse.min.js'
-	$(INSTALL) -D dist/converse.min.js.map 'converse-assets-$(VERSION)/converse.min.js.map'
-	$(INSTALL) -D dist/converse-headless.js 'converse-assets-$(VERSION)/converse-headless.js'
-	$(INSTALL) -D dist/converse-headless.min.js 'converse-assets-$(VERSION)/converse-headless.min.js'
-	$(INSTALL) -D dist/converse-headless.min.js.map 'converse-assets-$(VERSION)/converse-headless.min.js.map'
-	$(INSTALL) -D dist/converse.css 'converse-assets-$(VERSION)/dist/converse.css'
-	$(INSTALL) -D dist/converse.min.css 'converse-assets-$(VERSION)/dist/converse.min.css'
-	cp -r dist/webfonts 'converse-assets-$(VERSION)/dist/'
-	cp -r sounds 'converse-assets-$(VERSION)/'
-	find locale -type f -name '*.json' \
-		-exec $(INSTALL) -D '{}' 'converse-assets-$(VERSION)/{}' \;
-	zip -r 'converse-assets-$(VERSION).zip' 'converse-assets-$(VERSION)'
-	rm -rf 'converse-assets-$(VERSION)'
-
+	npm run pack
 
 ########################################################################
 ## Install dependencies

package.json

@@ -4,11 +4,12 @@
   "description": "Browser based XMPP chat client",
   "main": "dist/converse.min.js",
   "files": [
-    "dist/",
-    "locale/",
-    "src/",
     "CHANGES.md",
-    "README.md"
+    "README.md",
+    "dist/",
+    "locale/**/*.json",
+    "sounds/",
+    "src/"
   ],
   "scripts": {
     "converse.css": "webpack --type=css --mode=development && rm -r tmp",