Update package to Swift 4

Author: aciidgh

.gitignore

@@ -2,3 +2,4 @@
 /.build
 /Packages
 /*.xcodeproj
+Package.resolved

Package.swift

@@ -1,3 +1,6 @@
+// swift-tools-version:4.0
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
 /*
  This source file is part of the Swift.org open source project
 
@@ -11,8 +14,19 @@
 import PackageDescription
 
 let package = Package(
-    name: "Dealer",
+    name: "dealer",
+    products: [
+        .executable(name: "Dealer", targets: ["Dealer"]),
+    ],
     dependencies: [
-        .Package(url: "https://github.com/apple/example-package-deckofplayingcards.git", majorVersion: 3),
+        // Dependencies declare other packages that this package depends on.
+        .package(url: "https://github.com/apple/example-package-deckofplayingcards.git", from: "3.0.0"),
+    ],
+    targets: [
+        // Targets are the basic building blocks of a package. A target can define a module or a test suite.
+        // Targets can depend on other targets in this package, and on products in packages which this package depends on.
+        .target(
+            name: "Dealer",
+            dependencies: ["DeckOfPlayingCards"]),
     ]
 )