Implement "NSURL / String" operator.

Overriding a standard operator for a completely different use case like this is not normally recommended, but I think it is warranted here. It's certainly a lot better than "URLByAppendingPathComponent".

SwiftShell/Files.swift

@@ -10,3 +10,7 @@ import Foundation
 /** The default NSFileManager */
 public let Files = NSFileManager.defaultManager()
 
+/** Append file or directory url to directory url */
+public func / (leftpath: NSURL, rightpath: String) -> NSURL {
+	return leftpath.URLByAppendingPathComponent(rightpath)
+}

SwiftShellTests/Files_Tests.swift

@@ -9,6 +9,11 @@
 import SwiftShell
 import XCTest
 
-class Files_Tests: XCTestCase {
+class UrlAppendationOperator: XCTestCase {
 
+	func testUrlSlashString () {
+		XCTAssertEqual( NSURL(fileURLWithPath: "dir") / "file.txt", NSURL(fileURLWithPath: "dir/file.txt"))
+		XCTAssertEqual( NSURL(fileURLWithPath: "dir/") / "/file.txt", NSURL(fileURLWithPath: "dir/file.txt"))
+		XCTAssertEqual( NSURL(string: "dir")! / "file.txt", NSURL(string: "dir/file.txt"))
+	}
 }