Manually do a "git submodule update --init" in release:perform
Manually do a "git submodule update --init" in release:perform

release:perform clones the repo but doesn't initialize submodules, so we
have to initialize them manually, using the exec-maven-plugin, or our
tests will fail downstream, leaving an half-complete release where only
some artifacts have been deployed to the repo.
See http://mail-archives.apache.org/mod_mbox/maven-users/201403.mbox/%3CCAEayHEPXOakH0qsmC0mCCntbZu%3DBNOZ6htiusAjdufq9LH6PCw%40mail.gmail.com%3E

Change-Id: Iecccf55c0c287b8001747849ac20532f44f64e83

ozwillo/ozwillo-kernel,ozwillo/ozwillo-kernel,ozwillo/ozwillo-kernel