Use devDependencies consistently

'dependencies' in package.json get installed as well when installing
converse.js or @converse/headless in a 3rd party project, which is
unnecessary.

Makefile

@@ -124,11 +124,11 @@ stamp-npm: $(LERNA) package.json package-lock.json src/headless/package.json
 .PHONY: clean
 clean:
 	rm -rf node_modules stamp-npm
-	rm dist/*.min.js
-	rm css/*.min.css
-	rm css/*.map
-	rm css/*.zip
-	rm *.zip
+	rm -f dist/*.min.js
+	rm -f css/*.min.css
+	rm -f css/*.map
+	rm -f css/*.zip
+	rm -f *.zip
 
 .PHONY: dev
 dev: stamp-npm

package.json

@@ -52,6 +52,7 @@
     "eslint": "4.19.1",
     "eslint-plugin-lodash": "^2.3.3",
     "exports-loader": "^0.7.0",
+    "fast-text-encoding": "^1.0.0",
     "filesize": "^3.6.1",
     "formdata-polyfill": "^3.0.12",
     "hellojs": "^1.16.1",
@@ -62,7 +63,7 @@
     "jed": "1.1.1",
     "jquery": "3.2.1",
     "jsdoc": "^3.5.5",
-    "lerna": "^3.10.5",
+    "lerna": "^3.11.0",
     "lodash-template-loader": "^2.0.0",
     "lodash-template-webpack-loader": "jcbrand/lodash-template-webpack-loader",
     "long": "^3.1.0",
@@ -84,8 +85,5 @@
     "webpack": "^4.0.1",
     "webpack-cli": "^2.1.4",
     "xss": "^0.3.3"
-  },
-  "dependencies": {
-    "fast-text-encoding": "^1.0.0"
   }
 }

src/headless/package.json

@@ -21,7 +21,7 @@
     "url": "https://github.com/conversejs/converse.js/issues"
   },
   "gitHead": "9641dcdc820e029b05930479c242d2b707bbe8e2",
-  "dependencies": {
+  "devDependencies": {
     "backbone": "1.3.3",
     "backbone.browserStorage": "0.0.5",
     "es6-promise": "^4.1.0",