Improve team admin page loading times

It takes a long time for the team form to load currently, this is due to it waiting for the requests for the different collector targets to finish resolving. This should be improved and there are several possible routes to take:

• Lazy load collector targets #34
• Fetch collector targets in background when initially visiting page
• Don't block page display, instead show that the collector target input fields are still loading
• implement a caching solution in the backend