spec: make sure mocking is configured for swagger

fixes CNVS-10649

otherwise rspec 2 in rails 3 will complain about changing the
mocking after defining some example groups when running swagger specs
with other specs

Change-Id: I68a690789300f5a0bb620d6d5171432fa678a84e
Reviewed-on: https://gerrit.instructure.com/29070
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Bryan Madsen <bryan@instructure.com>
QA-Review: Bryan Madsen <bryan@instructure.com>
Reviewed-by: Jacob Fugal <jacob@instructure.com>

Author: ccutrer

spec/apis/swagger/swagger_helper.rb

@@ -2,4 +2,6 @@
   File.dirname(__FILE__),
   '..', '..', '..',
   'doc', 'api', 'fulldoc', 'html', 'swagger')
-$:.unshift(swagger_dir)
+$:.unshift(swagger_dir)
+
+require File.expand_path(File.dirname(__FILE__) + '/../../mocha_rspec_adapter')