Add UID of Trove assigned during installation (F20/EL6/EL7)

According to the latest SPECs used for F20/EL6/EL7 there is no
specific UID used for Trove.

Latest SPECs are available at
http://repos.fedorapeople.org/repos/openstack/openstack-icehouse/.

---snip---
getent passwd $USERNAME >/dev/null || \
  useradd -r -g $GROUPNAME -G $GROUPNAME -d $HOMEDIR -s /sbin/nologin \
    -c "$USERNAME Daemons" $USERNAME
---snap---

Change-Id: I651979d76f25692d30a8447d9e1a16ef6263696c
Merge "Add UID of Trove assigned during installation (F20/EL6/EL7)"