Changes for sprockets version update

- add manifest.js, this is now needed as part of the upgrade to sprockets, see https://github.com/rails/sprockets/blob/master/UPGRADING.md
- remove webdrivers, as now using chromedriver

Gemfile

@@ -40,6 +40,5 @@ group :test do
   gem "mocha"
   gem "simplecov"
   gem "timecop"
-  gem "webdrivers"
   gem "webmock", require: false
 end

Gemfile.lock

@@ -354,10 +354,6 @@ GEM
     unicorn (5.8.0)
       kgio (~> 2.6)
       raindrops (~> 0.7)
-    webdrivers (4.4.1)
-      nokogiri (~> 1.6)
-      rubyzip (>= 1.3.0)
-      selenium-webdriver (>= 3.0, < 4.0)
     webmock (3.8.3)
       addressable (>= 2.3.6)
       crack (>= 0.3.2)
@@ -405,7 +401,6 @@ DEPENDENCIES
   slimmer
   timecop
   uglifier
-  webdrivers
   webmock
 
 BUNDLED WITH

app/assets/config/manifest.js

@@ -0,0 +1,5 @@
+//= link_tree ../images
+//= link application.js
+//= link webchat.js
+//= link application.css
+//= link print.css

config/initializers/assets.rb

@@ -2,14 +2,3 @@
 
 # Version of your assets, change this if you want to expire all your assets.
 Rails.application.config.assets.version = "1.0"
-
-# Add additional assets to the asset load path.
-# Rails.application.config.assets.paths << Emoji.images_path
-
-# Precompile additional assets.
-# application.js, application.css, and all non-JS/CSS in the app/assets
-# folder are already added.
-Rails.application.config.assets.precompile += %w[
-  print.css
-  webchat.js
-]