Configurable dashboards via URL hash

One issue we've encountering is wanting to use dashboards as templates. For example - we might have a host metrics dashboard (CPU / memory / disk, etc), and having a separate tool that manages our hosts that might want to link to said dashboard for each host (i.e. http://statuswolf.example.com/dashboard/abcdef12345#host_id=XYZ)

This pull request allows us to upsert tags on each of the widgets for a dashboard via the window.location.hash. I attempted using real URL parameters (i.e. ?hostid=host1) but StatusWolf didn't like that with no code change, so I didn't go tracking that down.