Don't use parallel_tests under travis

Author: kpaulisse

rake/common.rb

@@ -1,4 +1,10 @@
 # Constants
 BASEDIR = File.expand_path('..', File.dirname(__FILE__)).freeze
 PUPPET_BINARY = File.join(BASEDIR, 'bin', 'puppet').freeze
-TEST_COMMAND = "parallel_rspec --suffix '_spec.rb$'".freeze
+TEST_COMMAND = begin
+  if ENV['TRAVIS']
+    "rspec --suffix '_spec.rb$'"
+  else
+    "parallel_rspec --suffix '_spec.rb$'"
+  end
+end.freeze