Add missing relationship implementation to InsertOrUpdate method

Removed a short-curcuit `return` and added an implementation to replace
a warning that should not have slipped through.
Merge pull request #20 from sbonami/20-Add-missing-relationship-implementation-to-InsertOrUpdate-method

Add missing relationship implementation to InsertOrUpdate method
Fix tests for changes in 2efb10f
Fix Rakefile so Travis test failures are properly reported
Modify Travis test procedures

This commit modified the travis test procedures so that we can have OS
X fail. Now, a build will finish as soon as a job has failed, or when
the only jobs left allow failures.
Merge pull request #22 from sbonami/22-Fix-travis.yml-so-failures-are-properly-reported

Fix Rakefile so Travis test failures are properly reported
Merge branch 'master' of https://github.com/sbonami/PFIncrementalStore into 21-Multiple-inserted-object-relationships-do-not-save

* 'master' of https://github.com/sbonami/PFIncrementalStore:
  Modify Travis test procedures
  Fix Rakefile so Travis test failures are properly reported
  Fix tests for changes in 2efb10f
  Add missing relationship implementation to InsertOrUpdate method