Updated openstack/openstack
Project: openstack/horizon  5b8170e5bd3fd23d87419a2522c21361cc5b11b6

Cell empty value defaults to - removing redundancy

The default value empty_value for a cell is horizon/tables/base.py
is "-", it is redundant and unnecessary to specify this column
definitions.

Closes-Bug: #1398904
Change-Id: Ica3e8f1559effe6b11f4e81d303758a869acbe2b