Since drained nodes could be (partially or fully) broken in iallocator,
we ignore results from these nodes when building the cluster map in
preparation for sending it to the script.

This is a cheap change for the stable branch; ideally we should not
query them at all.

The patch also fixes a typo in iallocator.rst.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>

This updates the iallocator documentation to 2.0, bumps up the
iallocator version (and moves a constants to lib/constants.py), and
fixes a style on install.rst.

Reviewed-by: ultrotter

This is a no-contents change, this doc will need update to conform to
2.0 message contents (and also the code will need increase to version 2
of the iallocator protocol).

Reviewed-by: imsnah