Install keepalived in neutron_l3_agent container
Install keepalived in neutron_l3_agent container

L3 HA requires keepalived. It has to be installed when install_type
is source.

Change-Id: I3265b74490559ca9b22a19917a76925a55e32cdd
Closes-bug: 1588829
(cherry picked from commit d511ee363be12c9d24929a6f02afef2e25031346)

negronjl/kolla,negronjl/kolla,negronjl/kolla