Log Message:
Update sysutils/salt to 2016.3.1.

There are a huge number of changes since the last pkgsrc update, way too
many to list here.  One of the more interesting changes for us though was
much improved support for Solaris and illumos.

For further details see the online changelogs here:

https://docs.saltstack.com/en/latest/topics/releases/2016.3.1.html
https://docs.saltstack.com/en/latest/topics/releases/2016.3.0.html
https://docs.saltstack.com/en/latest/topics/releases/2015.8.11.html
https://docs.saltstack.com/en/latest/topics/releases/2015.8.10.html
https://docs.saltstack.com/en/latest/topics/releases/2015.8.9.html
https://docs.saltstack.com/en/latest/topics/releases/2015.8.8.html
https://docs.saltstack.com/en/latest/topics/releases/2015.8.7.html

It appears there wasn't a 2015.8.6 release.