Update spec helper to match other ROM-style gems

spec/spec_helper.rb

@@ -1,8 +1,5 @@
 # encoding: utf-8
 
-require 'equalizer'
-require 'devtools/spec_helper'
-
 if ENV['COVERAGE'] == 'true'
   require 'simplecov'
   require 'coveralls'
@@ -14,13 +11,18 @@ if ENV['COVERAGE'] == 'true'
 
   SimpleCov.start do
     command_name 'spec:unit'
+
     add_filter 'config'
     add_filter 'spec'
+    add_filter 'vendor'
     add_filter 'test_app'
+
     minimum_coverage 90.1  # TODO: raise this to 100, then mutation test
   end
 end
 
+require 'equalizer'
+require 'devtools/spec_helper'
 require 'mutant'
 
 $LOAD_PATH << File.join(TestApp.root, 'lib')