Update dependency xcode@0.8.3 for security reason

[StefanoMagrassi]

I searched for your plugin through npms.io and it says that the package is insecure because of some outdated dependencies in the dependencies tree (see nodesecurity.io check).

In particular, xcode@0.8.3 uses node-uuid@1.3.3 which is insecure. In order to fix this issue, xcode package has to be upgraded to at least version 0.8.7 (which uses the node-uuid patched version 1.4.4).