Add macaroon inspection script

scripts-dev/dump_macaroon.py

+#!/usr/bin/env python2
+
+import pymacaroons
+import sys
+
+if len(sys.argv) == 1:
+    sys.stderr.write("usage: %s macaroon [key]\n" % (sys.argv[0],))
+    sys.exit(1)
+
+macaroon_string = sys.argv[1]
+key = sys.argv[2] if len(sys.argv) > 2 else None
+
+macaroon = pymacaroons.Macaroon.deserialize(macaroon_string)
+print macaroon.inspect()
+
+print ""
+
+verifier = pymacaroons.Verifier()
+verifier.satisfy_general(lambda c: True)
+try:
+    verifier.verify(macaroon, key)
+    print "Signature is correct"
+except Exception as e:
+    print e.message