created gridmap_flog client policy sub-package

 -> in the client package, use /usr/lib[64]/xtreemfs/policies as the directory for policies (this is currently realised through a hard-coded sed in the build scripts which need to be kept in sync with src/libxtreemfs/user_credentials_cache.cpp)

git-svn-id: https://xtreemfs.googlecode.com/svn/trunk@1645 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534