ACCUMULO-1658 System integration tests should default ACCUMULO_CONF_DIR to ACCUMULO_HOME/conf

Signed-off-by: John Vines <jvines@gmail.com>
Merge branch '1.4.5-SNAPSHOT' into 1.5.1-SNAPSHOT

Conflicts:
	test/system/auto/TestUtils.py
	test/system/continuous/agitator.pl