Update testing procedures with Travis

This commit updates the testing procedurs for TravisCI so that tests
can be run independently for each target. Additionally, the OS X target
was added as an allowable failure until further notice.
Remove OS X from podspec

This commit removes the OS X deployment target and dependencies from
the Podspec and Podfile.
Merge pull request #13 from sbonami/13-Temporarily-remove-support-for-OS-X

Temporarily remove support for OS X
Merge branch 'master' of https://github.com/sbonami/PFIncrementalStore into 4-Connect-PFIncrementalStore-with-backingPersistentStoreCoordinator

* 'master' of https://github.com/sbonami/PFIncrementalStore:
  Remove OS X from podspec
  Update testing procedures with Travis

Conflicts:
	Tests/Podfile