servers: better error messages when DB version is incorrect in DIR, removed...

servers: better error messages when DB version is incorrect in DIR, removed crash reports, print warning when using SingleFileStorageLayout (experimental stuff, don't use it)

git-svn-id: https://xtreemfs.googlecode.com/svn/trunk@1461 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534