[In progress] Fix copy resources script for iOS < 6 and OS X < 10.8

Remove the following flag from the script to avoid crashes

ibtool:

--reference-external-strings-file
              When combined with the --compile option, this flag indicates that the files in the Base.lproj locale  folder  should  be
              compiled  to reference the matching external strings files found in the other locales when loaded. Available on 10.8 and
              later.
[Complete] Fix copy resources script for iOS < 6 and OS X < 10.8
Merge branch 'master' of github.com:CocoaPods/CocoaPods
Update CHANGELOG
Update CHANGELOG.md
[Generator::CopyResourcesScript] Clean-up

See #1030
[Integration] Update fixtures for Generator::CopyResourcesScript

See #1030