Enable debug logging on tempest

With tempest moving to testr (serially currently) the log level is no
longer defaulting to debug as it did with nose. To get the same level
of verbosity in the logging as when running with nose this commit
sets the debug flag on tempest.

Change-Id: I6acd57be0f8188d31825d88471ba9883ebb30519
diff --git a/lib/tempest b/lib/tempest
index aaa7281..b97f0d8 100644
--- a/lib/tempest
+++ b/lib/tempest
@@ -201,6 +201,7 @@
     mkdir -p $TEMPEST_STATE_PATH
     iniset $TEMPEST_CONF DEFAULT use_stderr False
     iniset $TEMPEST_CONF DEFAULT log_file tempest.log
+    iniset $TEMPEST_CONF DEFAULT debug True
 
     # Timeouts
     iniset $TEMPEST_CONF compute build_timeout $BUILD_TIMEOUT