add .init() method to initialize the local store (#23)

* add .init() method to initialize the local store

* fix .travis.yml to meet latest dependency requirements

.travis.yml

@@ -1,5 +1,5 @@
 language: node_js
 node_js:
   - '8'
-  - '9'
   - '10'
+  - '12'

index.js

@@ -6,10 +6,12 @@ const { encrypt, decrypt } = require('caesar-encrypt')
 
 class SaveLocal {
   constructor(store = 'storage') {
-    const s = `.${store}`
+    this.store = `.${store}`
+  }
 
-    storage.init({
-      dir: join(homedir(), s)
+  async init() {
+    await storage.init({
+      dir: join(homedir(), this.store)
     })
   }
 

readme.md

@@ -17,6 +17,9 @@ const SaveLocal = require('save-local')
 
 const saveLocal = new SaveLocal('store')
 
+// you must call saveLocal.init() to initialize the instance
+await saveLocal.init()
+
 saveLocal.set({ name: 'token', value: 'my-token' })
 saveLocal.get('token').then(value => console.log(value))
 // => my-token
@@ -38,6 +41,12 @@ store name
 
 ### methods
 
+#### .init()
+
+Returns a `promise`
+
+Initializes the local store
+
 #### .set([options])
 
 Returns a `promise`