There is no duplicate check for TenantToConfig name

[Osteduden]

Somehow I manged to run a command twice so I ended up with two tenantconfig with the same name and values.
Without any warning or error. Next when I ran the New-ClientVM command I received an
"Warning: Cannot bind argument to parameter 'Path' because it is null"

When cleaning up the duplacte TenantConfig from the hvconfig.json all was good :)

[tabs-not-spaces]

so sounds like we need some kind of validation of existing tenant config?

[JonathanPitre]

Should be fixed in #32