Fixes issue with the boolean parameters that will always resolve to "tru...

From Örjan Sjöholm's comment: https://library.octopusdeploy.com/#!/step-template/actiontemplate-iis-apppool-create

> This change will fix the issue:
> $appPoolAutoStart = [boolean]::Parse($OctopusParameters['AppPoolAutoStart'])
> $appPoolEnable32BitAppOnWin64 = [boolean]::Parse($OctopusParameters['AppPoolEnable32BitAppOnWin64'])

See: http://www.jonathanmedd.net/2012/05/powershell-quick-tip-converting-a-string-to-a-boolean-value.html