New Post: App Catalog

Will do.
Is it safe to assume that \sites\ is the managed path for all web applications' site collections?
I'll be testing but the only proposed changes would be :

XMLinput

<AppManagementService Provision="SERVERNAME" Name="App Management Service" ProxyName="App Management Service" AppDomain="devapps.sitename.com" >
  <Database>
    <Name>AppManagement</Name>
    <DBServer />
    <DBAlias Create="false" DBInstance="SERVER\INSTANCE" DBPort="" />
  </Database>
==>  <AppCatalog Provision="true" Path="AppCatalog" Name="Application Catalog" />
</AppManagementService>

AutoSPInstallerFunctions.ps1

Function CreateAppCatalogSiteCollections ([xml]$xmlinput)
{
    if ($xmlinput.Configuration.AppManagementService.AppCatalog.Provision -eq $true )
    {
        if ($xmlinput.Configuration.WebApplications)
        {
            # Get Web Application URL
            foreach ($webApp in $($xmlinput.Configuration.WebApplications.WebApplication))
            {
                $webAppCatalogUrl = $($webApp.url)+":"+$($webApp.Port)+"/sites/"+$($xmlinput.Configuration.AppManagementService.AppCatalogPath)
                $webAppOwner = $($webapp.Configuration.Farm.Account.UserName)
                New-SPSite -Url $($webAppCatalogUrl) -OwnerAlias $(webAppOwner) -Name "App Catalog" -Template "APPCATALOG#0" 
                Update-SPAppCatalogConfiguration -site $($webAppCatalogUrl)  

            }
        }
    }
}

Changes to AUtoSPInstallerMain.ps1 IN FUNCTION Setup-Services

    if ($env:spVer -eq "15") # These are for SP2013 only
    {
        CreateAppManagementServiceApp $xmlinput
==>     CreateAppCatalogSiteCollections $xmlinput
        CreateSubscriptionSettingsServiceApp $xmlinput
        CreateWorkManagementServiceApp $xmlinput
        CreateMachineTranslationServiceApp $xmlinput
        CreateAccessServicesApp $xmlinput
        CreatePowerPointConversionServiceApp $xmlinput
        ConfigureDistributedCacheService $xmlinput
    }