fix(config): try to identify if wechaty is installed globally

src/config.ts

@@ -90,18 +90,29 @@ Object.assign(Config, {
  */
 Object.assign(Config, {
   isDocker:  isWechatyDocker(),
+  isGlobal:  isWechatyInstalledGlobal(),
 })
 
+function isWechatyInstalledGlobal() {
+  /**
+   * TODO:
+   * 1. check /node_modules/wechaty
+   * 2. return true if exists
+   * 3. otherwise return false
+   */
+   return false
+}
+
 function isWechatyDocker() {
   /**
-   * Continuous Integration System
+   * false for Continuous Integration System
    */
   if (isCi) {
     return false
   }
 
   /**
-   * Cloud9 IDE
+   * false Cloud9 IDE
    */
   const c9 = Object.keys(process.env)
                   .filter(k => /^C9_/.test(k))
@@ -110,6 +121,9 @@ function isWechatyDocker() {
     return false
   }
 
+  /**
+   * return indentify result by NPM module `is-docker`
+   */
   return isDocker()
 }