Extract <zipurlinstaller> from the <cargo-*> tasks

I would like to propose to move the ZipURLInstaller out of the <cargo-*> tasks. Indeed, the installer is something that should be used before calling the cargo tasks (same as when using the Java API).

Thus I propose to create a special task for the installer:

<cargo-installer installURL="..." installDir="..." homeDirProperty="..."/>

where homeDirProperty points to a property that will hold the location of the installed container home.