ACCUMULO-2332 Rework how address parsing is currently done by the GC.

Try to reduce the number of creations of an InetSocketAddress and ensure
that an externally addressable hostname/address is placed in zookeeper.
Also, replace 0.0.0.0 with the hostname for the machine when provided
as the address
ACCUMULO-2329 Infer the GC role from master when gc file is not present.