Fix exception handling in python3 (#1324)

**- What I did**
In python3, message is not an attribute of Exception. As a result, another exception will be thrown in exception handling code. 
```
"Traceback (most recent call last):", 
        "  File \"/usr/local/bin/fdbshow\", line 154, in <module>", 
        "    main()", 
        "  File \"/usr/local/bin/fdbshow\", line 150, in main", 
        "    print(e.message)", 
        "AttributeError: 'RuntimeError' object has no attribute 'message'"
```
This commit addressed the issue.

**- How I did it**
Relpace `e.message` with `str(e)`.

Signed-off-by: bingwang <[email protected]>

scripts/aclshow

@@ -212,7 +212,7 @@ def main():
         acls.previous_counters()
         acls.display_acl_stat(args.all)
     except Exception as e:
-        print(e.message, file=sys.stderr)
+        print(str(e), file=sys.stderr)
         sys.exit(1)
 
 if __name__ == "__main__":

scripts/ecnconfig

@@ -326,7 +326,7 @@ def main():
             sys.exit(1)
 
     except Exception as e:
-        print("Exception caught: ", e.message, file=sys.stderr)
+        print("Exception caught: ", str(e), file=sys.stderr)
         sys.exit(1)
 
 if __name__ == "__main__":

scripts/fdbclear

@@ -50,7 +50,7 @@ def main():
             fdb.send_notification("ALL", "ALL")
             print("FDB entries are cleared.")
     except Exception as e:
-        print(e.message)
+        print(str(e))
         sys.exit(1)
 
 if __name__ == "__main__":

scripts/fdbshow

@@ -147,7 +147,7 @@ def main():
         fdb = FdbShow()
         fdb.display(args.vlan, args.port)
     except Exception as e:
-        print(e.message)
+        print(str(e))
         sys.exit(1)
 
 if __name__ == "__main__":

scripts/lldpshow

@@ -201,7 +201,7 @@ def main():
         lldp.parse_info(lldp_detail_info)
         lldp.display_sum(lldp_detail_info)
     except Exception as e:
-        print(e.message, file=sys.stderr)
+        print(str(e), file=sys.stderr)
         sys.exit(1)
 
 

scripts/mmuconfig

@@ -151,7 +151,7 @@ def main(config):
             sys.exit(1)
 
     except Exception as e:
-        print("Exception caught:", e.message, file=sys.stderr)
+        print("Exception caught:", str(e), file=sys.stderr)
         sys.exit(1)
 
 if __name__ == "__main__":

scripts/natclear

@@ -63,7 +63,7 @@ def main():
             nat.send_statistics_notification("STATISTICS", "ALL")
             print("\nNAT statistics are cleared.")
     except Exception as e:
-        print(e.message)
+        print(str(e))
         sys.exit(1)
 
 if __name__ == "__main__":

scripts/natconfig

@@ -367,7 +367,7 @@ def main():
             nat.fetch_nat_zone()
             nat.display_nat_zone()
     except Exception as e:
-        print(e.message)
+        print(str(e))
         sys.exit(1)
 
 if __name__ == "__main__":

scripts/natshow

@@ -404,7 +404,7 @@ def main():
             nat.display_count()
 
     except Exception as e:
-        print(e.message)
+        print(str(e))
         sys.exit(1)
 
 if __name__ == "__main__":

scripts/nbrshow

@@ -261,7 +261,7 @@ def main():
             arp.display()
 
     except Exception as e:
-        print(e.message)
+        print(str(e))
         sys.exit(1)
 
 

scripts/portconfig

@@ -99,7 +99,7 @@ def main():
             sys.exit(1)
 
     except Exception as e:
-        print(e.message, file=sys.stderr)
+        print(str(e), file=sys.stderr)
         sys.exit(1)
 
 if __name__ == "__main__":

scripts/sonic_sku_create.py

@@ -631,7 +631,7 @@ def create_sku_dir(self):
         try:
             shutil.copytree(self.base_sku_dir, self.new_sku_dir)
         except OSError as e:
-            print(e.message, file=sys.stderr)
+            print(str(e), file=sys.stderr)
 
     def remove_sku_dir(self):
         # remove SKU directory 
@@ -653,7 +653,7 @@ def remove_sku_dir(self):
             else:
                 print("SKU directory: "+ self.new_sku_dir + " was NOT removed")
         except OSError as e:
-            print(e.message, file=sys.stderr) 
+            print(str(e), file=sys.stderr) 
 
     def platform_specific(self):
         # Function that checks for Platform specific restrictions