Make HTTPConditionalGetInfo serializable via a dictionary.

Frameworks/RSWeb/RSWeb/HTTPConditionalGetInfo.swift

@@ -8,23 +8,27 @@
 
 import Foundation
 
-public struct HTTPConditionalGetInfo: Codable {
+public struct HTTPConditionalGetInfo {
 	
 	public let lastModified: String?
 	public let etag: String?
+
 	public var isEmpty: Bool {
 		get {
 			return lastModified == nil && etag == nil
 		}
 	}
 	
-	public init(lastModified: String?, etag: String?) {
+	public init?(lastModified: String?, etag: String?) {
 
+		if lastModified == nil && etag == nil {
+			return nil
+		}
 		self.lastModified = lastModified
 		self.etag = etag
 	}
 	
-	public init(urlResponse: HTTPURLResponse) {
+	public init?(urlResponse: HTTPURLResponse) {
 	
 		let lastModified = urlResponse.valueForHTTPHeaderField(HTTPResponseHeader.lastModified)
 		let etag = urlResponse.valueForHTTPHeaderField(HTTPResponseHeader.etag)
@@ -32,6 +36,27 @@ public struct HTTPConditionalGetInfo: Codable {
 		self.init(lastModified: lastModified, etag: etag)
 	}
 
+	public var dictionary: [String: String]? {
+		get {
+			if lastModified == nil && etag == nil {
+				return nil
+			}
+			var d = [String: String]()
+			if let lastModified = lastModified {
+				d[HTTPResponseHeader.lastModified] = lastModified
+			}
+			if let etag = etag {
+				d[HTTPResponseHeader.etag] = etag
+			}
+			return d
+		}
+	}
+
+	public init?(dictionary: [String: String]) {
+
+		self.init(lastModified: dictionary[HTTPResponseHeader.lastModified], etag: dictionary[HTTPResponseHeader.etag])
+	}
+
 	public func addRequestHeadersToURLRequest(_ urlRequest: NSMutableURLRequest) {
 		
 		if let lastModified = lastModified {