Aspera client check

It's highly likely that if a Nuxeo system has the Aspera connector installed, only a handful of users of that system will need to upload and download via Aspera.

Currently the web ui checks for the local installation of the aspera client at entry (i.e. when a user loads the home/dashboard)

It would be better if there was no general check – the check for the client should only happen if a user goes to the Aspera Upload page or attempts to Download via Aspera.