BUG-7473: add Karaf 4 features

BUG-7473: add Karaf 4 features

Instead of switching wholesale to Karaf 4 only, this patch adds
duplicate features for Karaf 4:

* feature-repo-parent is the new parent for Karaf 4 feature
  repositories (the Karaf 3 parent is now feature3-repo-parent, used
  only in odlparent);
* single-feature-parent is the new parent for Karaf 4 features (the
  Karaf 3 parent is now single-feature3-parent, used only in
  odlparent);
* features4-akka is the new odlparent Karaf 4 feature repository for
  Akka (dropping the old, backwards-compatible features);
* features4-odlparent is the new odlparent Karaf 4 feature repository
  for all other features (again, dropping the old,
  backwards-compatible features).

For the time being, we use Karaf 4.0.7 as the container (otherwise we
run into issues caused by
https://issues.apache.org/jira/browse/FELIX-5450 at least in
controller), and our own release of 4.0.9-SNAPSHOT, called 4.0.8-odl,
for the Karaf Maven plugin (we need upcoming 4.0.9 features when
generating our feature descriptors).

features-parent isn't duplicated for Karaf 4, downstreams are
encouraged to use at least feature-repo-parent instead.

This patch includes the following changes too:
* bundle uninstall failures are ignored in SingleFeatureTest;
* the deprecated features are reduced to delegates for their
  replacement features (e.g. odl-akka-scala simply pulls in
  odl-akka-scala-2.11);
* karaf4-parent only pulls in standard and war (these two features
  include all the other features that were explicitly listed);
* Pax Exam is upgraded to 4.9.2 (necessary to build with Karaf 4, but
  backwards-compatible with Karaf 3);
* Jacoco is upgraded to 0.7.7.201606060606 (as above);
* pax-url is upgraded to 2.5.1 (as above);
* the Protobuf tweaking for clustering is no longer necessary and is
  removed;
* bundles-test needs wrap as a pre-requisite, which requires wrapping
  it in a feature (odl-bundles-test) and using that in the Karaf 4
  SingleFeatureTest;
* karaf4-parent supports karaf.localFeature again.

Change-Id: I251aa7aefe6d3d7f93a73b5256bad6e596147c66
Signed-off-by: Stephen Kitt <skitt@redhat.com>