Add an AssemblyExtensions extensions method class for Assembly object

[N1K0232]

I was thinking about this issue, because I saw some of your last web projects there's a file AssemblyExtensions.cs that provides a
generic GetAttribute method

The signature is:
public static string GetAttribute(this Assembly assembly, Func<T, string> value) where T : Attribute { }

This method would be helpful to avoid code duplication everytime
Hope it will be a good upgrade :)

EDIT: the github editor doesn't take the generic parameter in the method definition, but it was meaning to be a generic method