Cmdline arg -c sets main configuration file (old paths.conf) instead of dir containing it

It has been notified that current configuration system is difficult to
understand and to use, so it has been envisioned to refactor it a bit.
The idea is that the user passes a -c path/to/main.conf file, which in
turn contains whatever osmo-gsm-tester main settings supports (basically
what old paths.conf used to be, plus some files harcoded to the same -c
directory are now configurable through the main configuration file).

Change-Id: Ieca65b71b543c44cfcec8e83efd0fe053c432e55
diff --git a/selftest/resource_test/resource_test.ok b/selftest/resource_test/resource_test.ok
index bbdbc5b..8a0b52f 100644
--- a/selftest/resource_test/resource_test.ok
+++ b/selftest/resource_test/resource_test.ok
@@ -9,12 +9,14 @@
 ok, caused exception RuntimeError: Refusing to drop a list of resources from itself. This is probably a bug where a list of Resources() should have been copied but is passed as-is. use Resources.clear() instead.
 - test removing a Resources list from one with the same list in it
 - test resources config and state dir:
-cnf -: DBG: Found config file paths.conf as [PATH]/selftest/resource_test/conf/paths.conf in [PATH]/selftest/resource_test/conf which is [PATH]/selftest/resource_test/conf
-cnf -: DBG: [PATH]/selftest/resource_test/conf/paths.conf: relative path ./test_work/state_dir is [PATH]/selftest/resource_test/conf/test_work/state_dir
-cnf -: DBG: [PATH]/selftest/resource_test/conf/paths.conf: relative path ./suite_test is [PATH]/selftest/resource_test/conf/suite_test
-cnf -: DBG: Found path state_dir as [PATH]/selftest/resource_test/conf/test_work/state_dir
-cnf ResourcesPool: DBG: Found config file resources.conf as [PATH]/selftest/resource_test/conf/resources.conf in [PATH]/selftest/resource_test/conf which is [PATH]/selftest/resource_test/conf
-cnf ResourcesPool: DBG: Found path state_dir as [PATH]/selftest/resource_test/conf/test_work/state_dir
+cnf -: DBG: Found main configuration file in  [PATH]/selftest/resource_test/conf/paths.conf which is [PATH]/selftest/resource_test/conf/paths.conf
+cnf -: DBG: MAIN CONFIG:
+{'default_suites_conf_path': '[PATH]/selftest/resource_test/conf/default-suites.conf',
+ 'defaults_conf_path': '[PATH]/selftest/resource_test/conf/defaults.conf',
+ 'resource_conf_path': '[PATH]/selftest/resource_test/conf/resources.conf',
+ 'scenarios_dir': '[PATH]/selftest/resource_test/conf/scenarios',
+ 'state_dir': '[PATH]/selftest/resource_test/conf/test_work/state_dir',
+ 'suites_dir': '[PATH]/selftest/resource_test/conf/suite_test'}
 *** all resources:
 {'arfcn': [{'_hash': 'e620569450f8259b3f0212ec19c285dd07df063c',
             'arfcn': '512',