Closed Unassigned: Execute-MSI -Path parameter does not check if $msipath has a file Extension [123]

Execute-MSI 's -Path parameter does not check if $msipath has a file Extension (e.g. .msi)
If the file Extension is omitted you get this misleading error message:
```
[Installation] :: Error Record:
-------------
Message : The variable cannot be validated because the value is not a valid value for the WorkingDirectory variable.
InnerException :

FullyQualifiedErrorId : ValidateSetFailure

PositionMessage :
At ....\AppDeployToolkit\AppDeployToolkitMain.ps1:1994 char:29
+ [string]$workingDirectory <<<< = Split-Path -Path $msiFile -Parent
```

Also, Execute-MSI 's header comments should mention:
-LogName will have _Install.log appended

BTW: No rush on fixing this but keep up the awesome work. I'd post more nitpicks but I can tell you are busy as hell. I'm even debating changing my screen name since I think someone else more annoying than me.
Comments: I think it should be resolved. If there any more issues, please re-open the ticket.