BUG-2159: bump jacoco version

0.6.2 does not work with Java 8. Until
https://git.opendaylight.org/gerrit/11816 is merged, this fixes the
problem locally.

Change-Id: I3970e0e176190fb6180f0ea266bd10433c2d5afa
Signed-off-by: Robert Varga <rovarga@cisco.com>