Fixes default sitename in login sample and adds more print statements (#652)

(cherry picked from commit ccbbc49)

Author: Chris Shin

samples/login.py

@@ -22,7 +22,7 @@ def main():
     group = parser.add_mutually_exclusive_group(required=True)
     group.add_argument('--username', '-u', help='username to sign into the server')
     group.add_argument('--token-name', '-n', help='name of the personal access token used to sign into the server')
-    parser.add_argument('--sitename', '-S', default=None)
+    parser.add_argument('--sitename', '-S', default='')
 
     args = parser.parse_args()
 
@@ -36,13 +36,18 @@ def main():
     if args.username:
         # Trying to authenticate using username and password.
         password = getpass.getpass("Password: ")
+
+        print("\nSigning in...\nServer: {}\nSite: {}\nUsername: {}".format(args.server, args.sitename, args.username))
         tableau_auth = TSC.TableauAuth(args.username, password, site_id=args.sitename)
         with server.auth.sign_in(tableau_auth):
             print('Logged in successfully')
 
     else:
         # Trying to authenticate using personal access tokens.
-        personal_access_token = input("Personal Access Token: ")
+        personal_access_token = getpass.getpass("Personal Access Token: ")
+
+        print("\nSigning in...\nServer: {}\nSite: {}\nToken name: {}"
+              .format(args.server, args.sitename, args.token_name))
         tableau_auth = TSC.PersonalAccessTokenAuth(token_name=args.token_name,
                                                    personal_access_token=personal_access_token, site_id=args.sitename)
         with server.auth.sign_in_with_personal_access_token(tableau_auth):