Update underlying invocation of `xcodebuild -showBuildSettings` such that iOS Test Bundle Schemes function normally under Xcode 5.x. fixes #187

This change fixes test execution failures under Xcode 5 with the error message: `ERROR: Expected to receive build settings for 1 target`

* Add utility methods for introspecting the version of xcodebuild that xctool is interacting with
* Use the `test` action when introspecting the test environment under Xcode 5.x
* Use the `build` action when introspecting the test environment under Xcode 5.x
moving ArrayContainsSubsequence into a TestUtil so we can share.
change XcodebuildVersion() to use DTXcode from Xcode's Info.plist
XcodeSubjectInfo: attempt to fetch build settings from multiple actions.