Merge pull request #14 from selasie/fix/wait-until-task-exits

waiting until task actually completes before returning from xcrun method

Sources/XCResultKit/XCResultFile.swift

@@ -163,7 +163,9 @@ public class XCResultFile {
 
         let data = pipe.fileHandleForReading.readDataToEndOfFile()
         let output: String? = String(data: data, encoding: String.Encoding.utf8)
-
+
+        task.waitUntilExit()
+
         return output
     }
 }