Add webdrivers to gemfile if not present

Author: JonRowe

example_app_generator/generate_app.rb

@@ -32,6 +32,9 @@
   gsub_file "Gemfile", /.*gem..sqlite3.*/, "gem 'sqlite3', '~> 1.4'"
 
   gsub_file "Gemfile", /.*chromedriver-helper.*/, "gem 'webdrivers'"
+  if File.read('Gemfile') !=~ /gem 'webdrivers'/
+    append_to_file 'Gemfile', "gem 'webdrivers'\n"
+  end
 
   if RUBY_ENGINE == "jruby"
     gsub_file "Gemfile", /.*jdbc.*/, ''