[5.0] fix IPv4 vs IPv6 mismatch in gelf_test

[spoonincode]

gelf_test.py listens on 127.0.0.1,

leap/tests/gelf_test.py

Lines 71 to 74 in aef4329

	def gelfServer(stop):
	s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
	s.settimeout(1)
	s.bind((TestHelper.LOCAL_HOST, GELF_PORT))

but then configured its logging.json to use localhost. In 5.0, gelf will use IPv6 and on by box localhost will resolve to ::1 thus this test would fail locally for me since the gelf messages wouldn't arrive on the expected address.

Explicitly configure 127.0.0.1 in logging.json so it's always IPv4->IPv4

[ericpassmore]

Note:start
group: STABILITY
category: TEST
summary: Fix tests to use IPv4 for loopback.
Note:end