Adding UniMgr feature

Adding UniMgr feature

1) Feature Tests Pass: https://jenkins.opendaylight.org/releng/view/unimgr/job/unimgr-merge-beryllium/

2) Features Comply with Guidelines: https://git.opendaylight.org/gerrit/gitweb?p=unimgr.git;a=blob;f=features/src/main/features/features.xml;h=41026ead2607c4be5339b25680df257dcf8dba29;hb=HEAD
a) Feature Names: odl-unimgr
b) Features Descriptions: Present
c) Features Start-Levels: N/A

3) Features Tested: Features have been tested for functionality with
a) feature:install odl-unimgr
b) feature:install odl-unimgr odl-integration-compatible-with-all

4) Integration Test Impact: N/A

Change-Id: I423b91ed2607c0661ab20f9ca05fdf8bbd145885
Signed-off-by: adetalhouet <adetalhouet@inocybe.com>