Add support for atomic upgrades in PackageInfo generation

[xr1337]

Allow users to set bundle-upgrades and atomic-update-bundle in PackageInfo so that malicious attackers can not overwrite components/bundles during installation.

    <upgrade-bundle>
        <bundle id="com.myCompany.myApp"/>
    </upgrade-bundle>
    <update-bundle/>
    <atomic-update-bundle/>