update spring and binstub

fixes `bin/rake css:styleguide` and gemfile confusion

Change-Id: I4f46b9fdb2e610b4ff64af49b888f33aea0cdbdb
Reviewed-on: https://gerrit.instructure.com/92163
Tested-by: Jenkins
Reviewed-by: Rob Orton <rob@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>

Gemfile.d/development.rb

@@ -9,7 +9,7 @@ group :development do
   gem 'colorize', require: false
 
   gem "letter_opener"
-  gem 'spring', '>= 1.3.0'
+  gem 'spring', '>= 1.3.2'
   gem 'spring-commands-rspec', '1.0.2'
 
   # Option to DISABLE_RUBY_DEBUGGING is helpful IDE-based debugging.

bin/spring

@@ -1,18 +1,15 @@
 #!/usr/bin/env ruby
 
-# This file loads spring without using Bundler, in order to be fast
-# It gets overwritten when you run the `spring binstub` command
+# This file loads spring without using Bundler, in order to be fast.
+# It gets overwritten when you run the `spring binstub` command.
 
 unless defined?(Spring)
-  require "rubygems"
-  require "bundler"
+  require 'rubygems'
+  require 'bundler'
 
-  if match = Bundler.default_lockfile.read.match(/^GEM$.*?^    (?:  )*spring \((.*?)\)$.*?^$/m)
-    ENV["GEM_PATH"] = ([Bundler.bundle_path.to_s] + Gem.path).join(File::PATH_SEPARATOR)
-    ENV["GEM_HOME"] = ""
-    Gem.paths = ENV
-
-    gem "spring", match[1]
-    require "spring/binstub"
+  if (match = Bundler.default_lockfile.read.match(/^GEM$.*?^    (?:  )*spring \((.*?)\)$.*?^$/m))
+    Gem.paths = { 'GEM_PATH' => [Bundler.bundle_path.to_s, *Gem.path].uniq.join(Gem.path_separator) }
+    gem 'spring', match[1]
+    require 'spring/binstub'
   end
 end