Generate zip file HTTP URL and manage deletion of zip files

Once a locator has built the aggregated zip file described by GEODE-2416, we need that locator to expose an endpoint through the Admin REST api to allow access to that file (perhaps e.g. /exportedArtifact?exportId=foo or /exportedArtifact?name=myLogs.zip). After the zip file has been successfully downloaded, it should be deleted and the URL invalidated. Also, the URL should only be valid for some time period (say 24hrs) after which the file will be deleted and URL invalidated even if it is not downloaded, to prevent exported zip files from polluting the locator's disk. This URL should be returned in the 'export log' command result JSON rather than the file contents. [Cluster:Read] permissions should be required to access the URL if integrated security is enabled.