[VFS-483][RAM] Many suggestions to improve the RAM file provider. Refactor local data in org.apache.commons.vfs2.provider.ram.RamFileOutputStream.write(byte[], int, int).

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/vfs/trunk@1511560 13f79535-47bb-0310-9956-ffa450edef68