SW-705: Fix typo

MAC/Services/src/ObservationControl2.py

@@ -85,7 +85,7 @@ def main():
                           description='runs the observationcontrol service')
     parser.add_option('-b', '--broker', dest='broker', type='string', default=DEFAULT_BROKER,
                       help='Address of the qpid broker, default: %default')
-    parser.add_option("-e", "--exchange", dest="echange", type="string",
+    parser.add_option("-e", "--exchange", dest="exchange", type="string",
                       default=DEFAULT_BUSNAME,
                       help="Name of the exchange on the qpid broker, default: %default")
     parser.add_option('-V', '--verbose', dest='verbose', action='store_true',