Fix package uninstallation of the marketplace module by removing the remaining temporary directory

When the digital signature marketplace package is installed, a temporary directory is created in the bundles directory (<NUXEO_HOME>/nxserver/bundles) called nuxeo-platform-signature-web-5.5.jar <== this is a directory name, not a file name. That new temporary directory is never removed after the package installation is finished.

Upon a subsequent reinstallation attempt the nuxeo-platform-signature-web-5.5.jar file is extracted into that new temporary directory instead of being put inside the top "bundles" directory which prevents the package from successful installation.