Adds support for Swift Package Manager

Package.swift

@@ -0,0 +1,50 @@
+// swift-tools-version:5.3
+/*
+ Copyright (c) 2012-2019, Pierre-Olivier Latour
+ All rights reserved.
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions are met:
+ * Redistributions of source code must retain the above copyright
+ notice, this list of conditions and the following disclaimer.
+ * Redistributions in binary form must reproduce the above copyright
+ notice, this list of conditions and the following disclaimer in the
+ documentation and/or other materials provided with the distribution.
+ * The name of Pierre-Olivier Latour may not be used to endorse
+ or promote products derived from this software without specific
+ prior written permission.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ DISCLAIMED. IN NO EVENT SHALL PIERRE-OLIVIER LATOUR BE LIABLE FOR ANY
+ DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+import PackageDescription
+
+let package = Package(
+    name: "GCDWebServer",
+    platforms: [.macOS(.v10_10),
+      .iOS(.v9),
+      .tvOS(.v9)],
+    products: [
+      .library(name: "GCDWebServer", targets: ["GCDWebServer"])
+    ],
+    targets: [
+        .target(
+            name: "GCDWebServer",
+            dependencies: [],
+            path: "GCDWebServer",
+            cSettings: [
+            .headerSearchPath("Core"),
+            .headerSearchPath("Requests"),
+            .headerSearchPath("Responses")
+            ])
+    ]
+)