NMS-4209: Add a bunch of Cisco Nexus SNMP collection and graph definitions.
Squashed commit of the following:

commit cd93cdd59102026bd6fe21b8cf8b573cb83a6f1d
Merge: 0d2494e c9dc01c
Author: Jeff Gehlbach <jeffg@opennms.org>
Date:   Wed Mar 5 11:45:56 2014 -0500

    Merge branch '1.12' of github.com:OpenNMS/opennms into feature-nms-4209-nexus-support

commit 0d2494ea5c68c7708758b1c2525141dd1411c4ba
Merge: 2205d17 bd40135
Author: Jeff Gehlbach <jeffg@opennms.org>
Date:   Tue Mar 4 10:54:51 2014 -0500

    Merge branch '1.12' of github.com:OpenNMS/opennms into feature-nms-4209-nexus-support

commit 2205d173255089bec7ebe04902bad16913cf926f
Merge: 33136ed d1cba54
Author: Jeff Gehlbach <jeffg@opennms.org>
Date:   Fri Jan 3 10:42:34 2014 -0500

    Merge branch '1.12' of github.com:OpenNMS/opennms into feature-nms-4209-nexus-support

commit 33136ed6b32f3d98f38c343de311d3fabf6bef3e
Merge: d682307 86dbc24
Author: Jeff Gehlbach <jeffg@opennms.org>
Date:   Thu Dec 19 15:50:07 2013 -0500

    Merge branch '1.12' of github.com:OpenNMS/opennms into feature-nms-4209-nexus-support

commit d6823079f70d20152b3542e089bf7ccf59364bb3
Author: Jeff Gehlbach <jeffg@opennms.org>
Date:   Wed Dec 11 17:14:15 2013 -0800

    Further Nexus data collection and graph work from Yuri Bank

commit 79ea5aee2cfea4ec926f0220a818968536d6127f
Merge: da03f5b 4ffb321
Author: Jeff Gehlbach <jeffg@opennms.org>
Date:   Wed Dec 11 17:13:21 2013 -0800

    Merge branch '1.12' of github.com:OpenNMS/opennms into feature-nms-4209-nexus-support

commit da03f5bc85d08c35c09ae25e1b4854ec7deb55f9
Merge: cd7a3c7 3a58e45
Author: Jeff Gehlbach <jeffg@opennms.org>
Date:   Tue Dec 10 16:06:35 2013 -0800

    Merge branch '1.12' of github.com:OpenNMS/opennms into feature-nms-4209-nexus-support

commit cd7a3c7db033e1b461b03f7f6f6c61329c5256fc
Author: Jeff Gehlbach <jeffg@opennms.org>
Date:   Tue Dec 10 15:50:15 2013 -0800

    Fix cisco-nx-environmental so that we won't persist data for
    instances that don't exist in both the entitySensorStatusTable
    and entityPhysicalTable

commit b255a449bebd0720965e1fcb83e7b388daa30a74
Author: Jeff Gehlbach <jeffg@opennms.org>
Date:   Tue Dec 10 10:47:01 2013 -0800

    Initial commit of Eric Abrahamsen's work from NMS-4209, plus some tweaks and additions