xWinRMListener: Ability to generate automatically generate & use self-signed certificate

[TraGicCode]

#88 would be awesome to be able to pass a flag that informs the module to autogenerate a self signed certificate to be used with an instance of a resource.

Possible Example

xWinRMListener [String] #ResourceName       
{                                           
    Address = [string]                      
    Transport = [string]{ HTTP | HTTPS }    
    AutoGenerateSelfSignedCertificate = [boolean] { true | *false* }
    [DependsOn = [string[]]]                
    [Ensure = [string]{ Absent | Present }] 
    [PsDscRunAsCredential = [PSCredential]] 
}