Implemented delete
implemented Create
Adding File.Delete and File.Create test-helpers
Merge branch 'master' of git://github.com/ncvib/System.IO.Abstractions

Conflicts:
	TestHelpers.Tests/MockFileTests.cs
	TestingHelpers/MockFile.cs

Signed-off-by: Martin Evans <martindevans@gmail.com>
Fixed the tests in MockFileTests.cs being merged incorrectly

Signed-off-by: Martin Evans <martindevans@gmail.com>