hints doesn't work as expected if using hints child scope

[Gary.Wang]

1.In latest bollywood aggregator scope, I add the following definination in json file
...
- "quick_start_help": "false",
+ "quick_start_help": "true",
...

https://bazaar.launchpad.net/~hanloon-team/hanloon/bollywood_opt_keyword/revision/22

After it's installed in the device, scope shows youtube video items directly without hints displaying.
It looks like we still check on the deprecated 'hints_hide' field in aggregator library and don't use
hints if we can't find it. So hints view didn't get displayed.

2.we forget to write cache file to dismiss hints as well. So if above issue is fixed, scopes always stay hints view
and will never fetch child scope results after pulling down to refresh.