Download Citrix sources using manifest "source" field, rather than with wget

[dcloud-ca]

The download links for Citrix are dynamic, so they can't be hard-coded in the manifest. They have to be obtained at build-time by scraping the downloads page for a unique link. However, I don't know take that unique link and use it in the module "source" field, so instead the installers are downloaded via wget (which in turn requires giving the build environment network permissions). I think it'd be best to download the installers via the "source" field, if possible.

[dcloud-ca]

On second thought, the build environment would still need network permissions to obtain the download links, even if installer downloads are able to be done via manifest "source" field.