Fix make unit_tests target
Fix make unit_tests target

This will restrict nose to running in tests/unit. Probably only
a short-term fix. Longer-term fix will be dependent on how we
structure and run unit tests.

Change-Id: I7d4be5b982e076ff2623956e64b12cf4472c04f2

intel-hpdd/intel-manager-for-lustre,intel-hpdd/intel-manager-for-lustre,intel-hpdd/intel-manager-for-lustre