GRN2-45, GRN2-197: Upgrade Rails to 5.2.3 and removed sass-rails gem (#636)

* Removed deprecate sass-rails and replace with sassc-rails

* Upgraded to Rails 5.2.3

* Fixed travis

* Added back Spring code

* Fixed travis again

config/spring.rb

@@ -1,8 +1,8 @@
 # frozen_string_literal: true
 
-%w(
+%w[
   .ruby-version
   .rbenv-vars
   tmp/restart.txt
   tmp/caching-dev.txt
-).each { |path| Spring.watch(path) }
+].each { |path| Spring.watch(path) }