conf.base updates and memory limit tweaks.

conf.base updates and memory limit tweaks.

Rename conf.base to conf.base-SoFS, since it is SoFS-specific.  Add
conf.base-SoFS-1.5.3 and modify setup_samba.sh to look for a
version-specific file if it exists.

Revert default value of MEM to 256MB and add 128MB to it in any
release files (SoFS-1.5.2, SoFS-1.5.3) that tell the kernel to reserve
128MB for kdump.  This introduces more order dependencies when using
release files... but there are obvious advantages.  Updated GUIMEM to
be a nice round 704MB and set it to 1GB in recent release files
(SoFS-1.5.2, SoFS-1.5.3) since it now seems much easier to run out of
memory.

Update note in README about configuration order being important when
using release files.  Add new file TODO.

Signed-off-by: Martin Schwenke <martin@meltin.net>