Remove hard-coded ports form ring builder script

The swift ring builder script was hard-coded with the default ports.

The script now reads the ports from the configuration files under
/etc/swift if bind_port is specified. If bind_port is not specified
then the default ports are used.

Change-Id: Ic1b53d896f2deb23a0f31a7a457eeb20dd38ab5f
Merge "Remove hard-coded ports form ring builder script"