Update __str__ for Analytics model

[buckyroberts]

Update the __str__ method of the Analytics model to include the title of the AnalyticsCategory as well. This is because when adding analytics data such as "Facebook followers" it is difficult to determine which of the options are for "Facebook followers" vs "Twitter followers", "Instagram followers", etc...

[ThaDeveloper]

@buckyroberts This has been updated, but we probably need to restructure AnalyticsCategory and Analytics to prevent reverse filter to get the category title unless it affects our current use case. Instead of having Analytics as many to many field on AnalyticsCategory, we can have AnalyticsCategory as a FK on Analytics model.