CernVM-FS preload capability

CernVM-FS (CVMFS) is a service for fast and reliable software distribution on a global scale. Data is organized in repositories. Files and metadata are downloaded on-demand by means of HTTP requests and take advantage of several layers of caches. The current per-file granularity of distribution and caching leads to poor performance especially in case of cold caches. In particular, loading of interdependent files and libraries required for certain applications can be improved. The goal of this project is to introduce the concept of bundles, which would improve the startup performance of applications.