TESTS: Start fixing up the tests so we can test-suite them properly

Dont call READCAPACITY from every single test.
Remove two arguments from the test signatures and turn them into globals.
remove the ret++ silliness.  Tests return 0 : all ok, -2, skipped or -1 : test failed

test-tool/1120_persistent_register_simple.c

@@ -25,8 +25,7 @@
 
 
 
-int T1120_persistent_register_simple(const char *initiator, const char *url,
-    int data_loss, int show_info)
+int T1120_persistent_register_simple(const char *initiator, const char *url)
 { 
 	struct iscsi_context *iscsi;
 	int ret, lun;