Add interactive option

This will keep passwords secret when running from the command line.

python/lsst/verify/bin/dispatchverify.py

@@ -75,6 +75,7 @@
 import argparse
 import os
 import json
+import getpass
 
 try:
     import git
@@ -128,6 +129,12 @@ def parse_args():
         default=False,
         help='Ignore data blobs even if they are available in the verification'
              'job.')
+    parser.add_argument(
+        '--interactive',
+        dest='interactive',
+        action='store_true',
+        default=False,
+        help='If set, prompt for password on the command line.')
 
     env_group = parser.add_argument_group('Environment arguments')
     env_group.add_argument(
@@ -394,7 +401,11 @@ def __init__(self, args):
             message = '--user or $SQUASH_USER configuration required'
             raise RuntimeError(message)
 
-        self.api_password = args.api_password or os.getenv('SQUASH_password')
+        if args.interactive:
+            self.api_password = getpass.getpass(prompt="SQuaSH password: ")
+        else:
+            self.api_password = (args.api_password
+                                 or os.getenv('SQUASH_password'))
         if not self.test and self.api_password is None:
             message = ('--password or $SQUASH_password configuration '
                        'required')