"crawl fire" satisfies test_crawl_fire_log_path
 - refactored get_config to go by cmdline, environment, default
 - refactored get_logger to go by cmdline, config, default
Use precedence now built into get_logger()
test_crawl_cfgdump_nosuch is satisfied
test_get_config_def_*() are satisfied
 - manage moving into and out of the test directory
 - soften 'test.d' to self.testdir
 - add test_get_config_*() stubs
 - helper routines: self.cd(), self.clear_env(), self.tearDown()
test_get_config_*() are all satisfied