libxtreemfs-java: Offset in write/read operations is now long. Makes possible...

libxtreemfs-java: Offset in write/read operations is now long. Makes possible to write/read long sized files. 

git-svn-id: https://xtreemfs.googlecode.com/svn/trunk@2986 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534