Enable link to Harvest page in User Dashboard

[mwengren]

CKAN does not have a way to navigate to the /harvest page in the UI, oddly.

If data providers are going to maintain harvests in CKAN directly, instead of via Registry, we need to add a link so they know where to go.

Preferred solution is to add a 'My Harvests' tab in the User Dashboard page (https://data.ioos.us/dashboard/) that a user can see one logged in to CKAN.

This would be a simple link that goes to https://data.ioos.us/harvest, as there's no way to filter the lists of harvests by Organization.

[mwengren]

@benjwadams added a Harvests menu item to the top of the CKAN common menu (shows on all pages a la: https://data.ioos.us/).

We should still consider adding a 'My Harvests' menu item to the user dashboard. In particular, if #240 is doable, it would make sense to have an option that filters harvests listed according to the logged in user's Org permissions (aka My Harvests).