Use InetAddresses.forString instead of InetAddress.getByName

Use InetAddresses.forString instead of InetAddress.getByName

Unlike InetAddress.getByName(), Guava's InetAddresses.forString()
never cause DNS services to be accessed.
JDK equivalents whenever you are expecting
to handle only IP address string literals,
so there is no blocking DNS penalty for a malformed string.

See:
https://google.github.io/guava/releases/22.0/api/docs/com/google/common/net/InetAddresses.html#forString-java.lang.String-

Change-Id: I7972c09f1f0a3a2688021302acbf6df112be7f72
Signed-off-by: Marek Gradzki <mgradzki@cisco.com>