Stop catching non error throwables such as SystemExit

        * Convert "except:" to "except Exception:"
        * Use log.exception instead of directly calling traceback
        * Remove unused imports
        * Fix a typos
        * Replace tabs with spaces for combatibility issues
diff --git a/TestON/tests/PingallExample/PingallExample.py b/TestON/tests/PingallExample/PingallExample.py
index 653397e..dab380f 100644
--- a/TestON/tests/PingallExample/PingallExample.py
+++ b/TestON/tests/PingallExample/PingallExample.py
@@ -127,7 +127,7 @@
             response = main.Mininet1.getSwController( "s" + str( i ) )
             try:
                 main.log.info( str( response ) )
-            except:
+            except Exception:
                 main.log.info( repr( response ) )
             if re.search( "tcp:" + ONOS1Ip, response ):
                 mastershipCheck = mastershipCheck and main.TRUE