Change default DMaaP hostname

Change default DMaaP hostname

The changes are for the purpose of allowing DMAAPHOST environmental
variable to accept either hostname and IP address.  If it is IP
address, the resolution for default dmaap hostname is written to
/etc/hosts; if hostname,an alias is created in /etc/host.aliases
for the default dmaap hostname.
(for the hostname aliasing to work, chnage default dmaap hostname
to onap-dmaap, no domain).

Change-Id: I58583cc5b678a29b54d8baecbd0b7bec621f7c8f
Signed-off-by: Lusheng Ji <lji@research.att.com>
Issue-ID: DCAEGEN2-235