Capture asset deletion in discovery

[bsushmith]

Is your feature request related to a problem? Please describe.
In the current data discovery system, whenever an asset(eg: table/job) gets deleted, the deletion information is not passed down to the compass from the meteor., and compass will show these deleted assets.

Meteor should capture these deletes and pass down the information to compass service so that it can process them accordingly.

Options:

1. capture asset delete at source by reading logs or through hooks
2. do a timely reconciliation between source and compass asset lists.