Attributes for files and directories that must not exist.

[IanG]

Hi Nate,

as promised in the issues log in your repo I've added some new DataNotations/Attributes that allow you to specify that files or directories must not exist (Along with tests).

You can use these like so:

File:

[FileNotExists]
public string File { get; }

Directory:

[DirectoryNotExists]
public string Dir { get; }

Either:

[FileOrDirectoryNotExists]
public string Path { get; }

Maybe they are useful ?

[natemcmaster]

Looks great! Thanks for the contribution!