Ignore automatically generated .xcworkspace files under .xcproject
Ignore automatically generated .xcworkspace files under .xcproject

[Finishes #99626768]

Signed-off-by: Sam Zhang <6f644ccdad72d240154cfc5bcf68e85ee907c580@pivotal.io>

gudatcomputers/PivotalCoreKit,jfuchs/PivotalCoreKit,idoru/PivotalCoreKit,pivotal/PivotalCoreKit,briancroom/PivotalCoreKit,pivotaltracker/PivotalCoreKit,gudatcomputers/PivotalCoreKit,jfuchs/PivotalCoreKit,idoru/PivotalCoreKit