Add eslint config and fix linting issues

src/util/Constants.js

@@ -1,6 +1,6 @@
 'use strict';
 
-exports.WhatsWebURL = 'https://web.whatsapp.com/'
+exports.WhatsWebURL = 'https://web.whatsapp.com/';
 
 exports.UserAgent = 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.109 Safari/537.36';
 
@@ -9,13 +9,13 @@ exports.DefaultOptions = {
         headless: true
     },
     session: false
-}
+};
 
 exports.Status = {
     INITIALIZING: 0,
     AUTHENTICATING: 1,
     READY: 3
-}
+};
 
 exports.Events = {
     AUTHENTICATED: 'authenticated',
@@ -25,7 +25,7 @@ exports.Events = {
     MESSAGE_CREATE: 'message_create',
     QR_RECEIVED: 'qr',
     DISCONNECTED: 'disconnected'
-}
+};
 
 exports.MessageTypes = {
     TEXT: 'chat',
@@ -35,25 +35,25 @@ exports.MessageTypes = {
     VIDEO: 'video',
     DOCUMENT: 'document',
     STICKER: 'sticker'
-}
+};
 
 exports.ChatTypes = {
     SOLO: 'solo',
     GROUP: 'group',
     UNKNOWN: 'unknown'
-}
+};
 
 exports.WAState = {
-    CONFLICT: "CONFLICT",
-    CONNECTED: "CONNECTED",
-    DEPRECATED_VERSION: "DEPRECATED_VERSION",
-    OPENING: "OPENING",
-    PAIRING: "PAIRING",
-    PROXYBLOCK: "PROXYBLOCK",
-    SMB_TOS_BLOCK: "SMB_TOS_BLOCK",
-    TIMEOUT: "TIMEOUT",
-    TOS_BLOCK: "TOS_BLOCK",
-    UNLAUNCHED: "UNLAUNCHED",
-    UNPAIRED: "UNPAIRED",
-    UNPAIRED_IDLE: "UNPAIRED_IDLE"
-}
+    CONFLICT: 'CONFLICT',
+    CONNECTED: 'CONNECTED',
+    DEPRECATED_VERSION: 'DEPRECATED_VERSION',
+    OPENING: 'OPENING',
+    PAIRING: 'PAIRING',
+    PROXYBLOCK: 'PROXYBLOCK',
+    SMB_TOS_BLOCK: 'SMB_TOS_BLOCK',
+    TIMEOUT: 'TIMEOUT',
+    TOS_BLOCK: 'TOS_BLOCK',
+    UNLAUNCHED: 'UNLAUNCHED',
+    UNPAIRED: 'UNPAIRED',
+    UNPAIRED_IDLE: 'UNPAIRED_IDLE'
+};