Trying to address failures for tests tied to analysis_group

- In previouvs versions `analysis_group` is either set or not set, and we had
`nargs` set to `?`
- We changed it to `+` to accept 1 or more arguments. We probably would like to
have 0 or more arguments for `analysis_group` - so changing `nargs` to `*`

Author: slack0

iotile_analytics_interactive/iotile_analytics/interactive/scripts/analytics_host.py

@@ -121,7 +121,7 @@ def build_args():
     parser.add_argument('--web-push-slug', type=str, default=None, help="Override the source slug given in the analysisgroup and force it to be this")
     parser.add_argument('--token', type=str, default=None, help="Token for authentication to iotile cloud (instead of a password)")
     parser.add_argument('-d', '--domain', default=DOMAIN_NAME, help="Domain to use for remote queries, defaults to https://iotile.cloud")
-    parser.add_argument('analysis_group', default=None, nargs='+', help="The slug or path of the object you want to perform analysis on")
+    parser.add_argument('analysis_group', default=None, nargs='*', help="The slug or path of the object you want to perform analysis on")
 
     return parser