Provide property to return parent directory on DirectoryPath

[pascalberger]

Currently getting the parent directory of a DirectoryPath requires some additional steps. Having a DirectoryPath.Parent property would be helpful.

[patriksvensson]

Sounds good, but should be a method unless we construct this at the point that the directory is created.

[LagunaElectric]

Hello! I'm new to this and would like to try tackling this issue :)

[LagunaElectric]

Wow that was fast!

[augustoproiete]

Awesome @LagunaElectric assigned it to you and looking forward to the PR!

[LagunaElectric]

Mind if I ask for directions to DirectoryPath declaration?

[augustoproiete]

https://github.com/cake-build/cake/blob/v1.1.0/src/Cake.Core/IO/DirectoryPath.cs