fix: revert to npm install

npm/install.js

@@ -139,23 +139,11 @@ const tasks = {
     })
   },
   /**
-   * Install Yarn
-   */
-  installYarn() {
-    ora.text = 'Installing Yarn...'
-    return exec.stdout('npm', ['install', 'yarn'], {
-      cwd: installDir
-    }).then(results => {
-      ora.text = 'Yarn installed successfully.'
-      return true
-    })
-  },
-  /**
    * Install npm dependencies
    */
   installDependencies() {
     ora.text = 'Installing Wiki.js npm dependencies...'
-    return exec.stdout('./node_modules/.bin/yarn', ['install', '--production', '--ignore-optional'], {
+    return exec.stdout('npm', ['install', '--only=production', '--no-optional'], {
       cwd: installDir
     }).then(results => {
       ora.text = 'Wiki.js npm dependencies installed successfully.'
@@ -260,9 +248,6 @@ Promise.join(
   isContainerBased && console.info('>> Creating config file...')
   return tasks.ensureConfigFile()
 }).then(() => {
-  isContainerBased && console.info('>> Installing Yarn...')
-  return tasks.installYarn()
-}).then(() => {
   isContainerBased && console.info('>> Installing dependencies...')
   return tasks.installDependencies()
 }).then(() => {

npm/package-lock.json

 {

npm/package.json

 {
   "name": "wiki.js",
-  "version": "1.0.2",
+  "version": "1.0.3",
   "description": "A modern, lightweight and powerful wiki app built on NodeJS, Git and Markdown",
   "main": "install.js",
   "scripts": {

package.json

 {
   "name": "wiki",
-  "version": "1.0.2",
+  "version": "1.0.3",
   "description": "A modern, lightweight and powerful wiki app built on NodeJS, Git and Markdown",
   "main": "wiki.js",
   "scripts": {