NMS-6937 - Upgrade embedded Karaf to 2.4.0

This allows running under Java 7 *or* 8.

Squashed commit of the following:

commit 38c2bd8b5fc22a178fe0954d5924029f66c9541a
Author: Benjamin Reed <ranger@opennms.org>
Date:   Thu Oct 16 16:16:34 2014 -0400

    allow 1.7 or 1.8

commit 44714b7b3ebdee05db7385e5e22566dd64fb5310
Author: Donald Desloge <thedesloge@gmail.com>
Date:   Thu Oct 16 15:28:22 2014 -0400

    Update OSGi services widgetset property to init.widgetset for ops4j pax-web bug in karaf 2.4.0

commit d1eeb531f42b42b5b1efed67849421d8beac0909
Merge: 890647e 5d97ddf
Author: Seth Leger <seth@opennms.org>
Date:   Tue Oct 14 17:07:31 2014 -0400

    Merge branch 'rc/stable/1.14.0' into features/karaf-2.4.0

commit 890647e6ee751fbddcf1662637a6bb1da1b78d32
Author: Benjamin Reed <ranger@opennms.org>
Date:   Tue Oct 14 10:48:54 2014 -0400

    failed to add this before because it was excluded

commit 75786406e37672ce9ea4a79b98a9f69bbef10e69
Author: Benjamin Reed <ranger@opennms.org>
Date:   Fri Oct 10 14:51:04 2014 -0400

    webapps are starting again, but missing resources

commit 61847cd57b4268b88a180e7d1bccf3260ba2a966
Merge: 7537810 8df76f0
Author: Benjamin Reed <ranger@opennms.org>
Date:   Thu Oct 9 15:13:59 2014 -0400

    Merge remote-tracking branch 'origin/rc/stable/1.14.0' into features/karaf-2.4.0

commit 7537810f2cf76a318eba458a4ecbdcc44bccc9ab
Author: Benjamin Reed <ranger@opennms.org>
Date:   Thu Oct 9 15:13:43 2014 -0400

    more rearranging/cleanup for karaf support

commit 85664844259f42590a524cc4b2c819d50d7b6952
Author: Benjamin Reed <ranger@opennms.org>
Date:   Wed Oct 8 17:43:12 2014 -0400

    fix taglib resolution error https://issues.apache.org/jira/browse/SMX4-1876

commit 271c9c6158b5eb35f22bc40224c07e825bd1a5c6
Author: Benjamin Reed <ranger@opennms.org>
Date:   Mon Sep 22 16:54:05 2014 -0400

    not yet compiling

commit 6e0cc0539efc4ba992820416c6d7fd2b572ac87c
Author: Benjamin Reed <ranger@opennms.org>
Date:   Thu Jun 5 17:01:55 2014 -0500

    more fixes, does not actually run though

commit e2c574a0fed97ce37b620517856b2d4064dced5b
Author: Benjamin Reed <ranger@opennms.org>
Date:   Wed Oct 8 16:29:20 2014 -0400

    well, we build now

commit f2f2301e526b3eb17f5c423a4552b01086fc0d25
Merge: 8edf7cb 51d2a38
Author: Benjamin Reed <ranger@opennms.org>
Date:   Wed Oct 8 15:41:38 2014 -0400

    Merge remote-tracking branch 'origin/rc/stable/1.14.0' into features/karaf-2.4.0

commit 8edf7cb8cd4cb2993b742ded9a47ae9f28d6d559
Author: Benjamin Reed <ranger@opennms.org>
Date:   Wed Oct 1 14:27:07 2014 -0400

    update everything to karaf 2.4.0; need to fix features-maven-plugin before we can build