Drop bowser, which is no longer used

Vendorfile

@@ -74,7 +74,6 @@ folder 'vendor/assets' do
 
   folder 'javascripts' do
     file 'html5shiv.js', 'https://raw.githubusercontent.com/aFarkas/html5shiv/master/src/html5shiv.js'
-    file 'bowser.js', 'https://github.com/lancedikson/bowser/releases/download/2.7.0/es5.js'
   end
 
   folder 'swfobject' do

app/assets/javascripts/index.js

@@ -20,7 +20,6 @@
 //= require index/changeset
 //= require index/query
 //= require router
-//= require bowser
 //= require querystring
 
 $(document).ready(function () {

config/eslint.json

@@ -7,7 +7,6 @@
     "eslint:recommended"
   ],
   "globals": {
-    "bowser": "readonly",
     "I18n": "readonly",
     "L": "readonly",
     "OSM": "writable",