Remove useless nested JARs

There are still a few nested JARs in Nuxeo, some of them should be moved into normal lib/, and some of them are useless:

• nuxeo-platform-mimetype-core-5.6-SNAPSHOT.jar-jmimemagic.jar
• nuxeo-platform-seam-debug-5.6-SNAPSHOT.jar-WEB_lib_jboss-seam-debug-2.1.0.SP1.jar
• nuxeo-platform-ui-web-5.6-SNAPSHOT.jar-WEB_lib_oscache-2.3.2.jar
• nuxeo-platform-ui-web-5.6-SNAPSHOT.jar-WEB_lib_standard-1.1.2.jar
• nuxeo-platform-ui-web-compat-5.6-SNAPSHOT.jar-WEB_lib_tomahawk-1.1.5-NXP-2749.jar
• nuxeo-platform-ui-web-compat-5.6-SNAPSHOT.jar-WEB_lib_tomahawk-sandbox-1.1.5-NXP-2749.jar
• nuxeo-platform-webapp-base-5.6-SNAPSHOT.jar-lib_com.noelios.restlet-1.0.7.jar
• nuxeo-platform-webapp-base-5.6-SNAPSHOT.jar-lib_com.noelios.restlet.ext.servlet-1.0.7.jar
• nuxeo-platform-webapp-base-5.6-SNAPSHOT.jar-lib_org.restlet-1.0.7.jar
• nuxeo-platform-webapp-base-5.6-SNAPSHOT.jar-lib_org.restlet.ext.fileupload-1.0.7.jar

Plus nested jars are kept in the tmp/nested-jars directory when restarting the server (and not cleaned up correctly) => need to clear this dir when testing changes.