Describe the bug

If island has no connection to the internet, the version update gets stuck waiting for the timeout and user can't do anything on the island on the meantime. Related #858

To Reproduce

Steps to reproduce the behavior:

1. Run island without internet connection
2. Refresh the island page
3. On each refresh island tries to query for version update and hangs until timeout is reached. Hanging occurs because Tornado WSGI container (as noted in a warning here) is blocking/synchronous server. All other requests doesn't get parsed until version update timeout is reached and execution gets resumed.

Expected behavior

Version update process should happen in parallel with other activities on the island.