[PATCH 2/2] docs-rst: conf.py: only setup notice box colors if Sphinx < 1.6

Sphinx 1.5 added a new way to change backward colors for note boxes, but kept backward compatibility with 1.4. On Sphinx 1.6, the old way stopped working, in favor of a new less hackish way. Unfortunately, this is currently too buggy to be used, and the old way doesn't work anymore. So, we have

[PATCH 2/2] docs-rst: conf.py: only setup notice box colors if Sphinx < 1.6

Sphinx 1.5 added a new way to change backward colors for note boxes, but kept backward compatibility with 1.4. On Sphinx 1.6, the old way stopped working, in favor of a new less hackish way. Unfortunately, this is currently too buggy to be used, and the old way doesn't work anymore. So, we have