add feature to filter collection records with in an agency and UI filter to see all child datasets of a parent dataset

[kvuppala]

Add feature to

• filter collection records with in an agency
• represent the parent records through an icon on the organization page
• UI filter to see all child datasets of a parent dataset

Currently it is possible to identify collection records and their child records through custom search queries:

Query for finding all parent datasets : https://inventory.data.gov/organization/small-business-administration?q=is_parent%3Atrue&sort=score+desc%2C+metadata_modified+desc

Finding the CKAN ID of a given parent dataset: https://inventory.data.gov/api/rest/dataset/small-business-profiles-for-the-states-and-territories-2014-20160204113221-2016041911-20161102103122
"id": "76b2f886-beb9-4d93-a7ca-cdc85cdf64ea"

Finding the child datasets which have the above ID as the parent dataset in their metadata: https://inventory.data.gov/organization/small-business-administration?q=parent_dataset%3A%2276b2f886-beb9-4d93-a7ca-cdc85cdf64ea%22&sort=score+desc%2C+metadata_modified+desc