[do not merge] Add foreman-plugins-nonscl-nightly-rhel* tags

[domcleal]

Allow building of a package in a non-SCL manner, or in both SCL and
non-SCL tags through the koji-foreman-plugins releaser.

Will be merged on Weds when I plan to make the corresponding changes to the foreman-plugins-nightly-* tags in Koji (https://groups.google.com/forum/#!topic/foreman-dev/RUeJtbnGBBA).

copy-tags-commands.sh generates this for plugins:

$ koji/copy-tags-commands.sh nightly 1.10
clone foreman-plugins-nightly-fedora19 foreman-plugins-1.10-fedora19
clone foreman-plugins-nightly-nonscl-rhel6 foreman-plugins-1.10-nonscl-rhel6
clone foreman-plugins-nightly-nonscl-rhel7 foreman-plugins-1.10-nonscl-rhel7
clone foreman-plugins-nightly-rhel6 foreman-plugins-1.10-rhel6
kkoji add-tag-inheritance --priority=10 foreman-plugins-1.10-rhel6 foreman-plugins-1.10-nonscl-rhel6
clone foreman-plugins-nightly-rhel7 foreman-plugins-1.10-rhel7
kkoji add-tag-inheritance --priority=10 foreman-plugins-1.10-rhel7 foreman-plugins-1.10-nonscl-rhel7
kkoji add-tag-inheritance --priority=10 foreman-plugins-1.10-fedora19-build foreman-1.10-fedora19
kkoji add-tag-inheritance --priority=10 foreman-plugins-1.10-rhel6-build foreman-1.10-rhel6
kkoji add-tag-inheritance --priority=10 foreman-plugins-1.10-rhel7-build foreman-1.10-rhel7
kkoji add-tag-inheritance --priority=10 foreman-plugins-1.10-nonscl-rhel6-build foreman-1.10-nonscl-rhel6
kkoji add-tag-inheritance --priority=10 foreman-plugins-1.10-nonscl-rhel7-build foreman-1.10-nonscl-rhel7

Should lead to a tag inheritance layout looking like this for SCL OSes:

foreman-plugins
  foreman-plugins-nonscl
    foreman-nonscl
  foreman
    [ foreman-nonscl ]

[domcleal]

Merged in 3ae1a2c.