Handle show object in invalid group

[will-moore]

Fixes #236

To test:

• Remove a user from a group where they have some data e.g. a Project (remember it's ID)
• Log them out, then log them in again, and try to load the project: /webclient/?show=project-1
• The webclient should load showing their default group (but not finding any Project) - instead of recursively re-loading the page.

[pwalczysko]

I have the behaviour repeated now without this PR on https://merge-ci.openmicroscopy.org/web/webclient/?show=project-33957, login as import_test_user.

Will check when this PR is in the build.

[pwalczysko]

this works on merge-ci now as expected. Logging in and out as different users, going via Search or just clicking on the link had the expected effect of landing in the default group of the user in question. No bliniking, the public user could be navigated too, and the login button worked also for other users.

Ready to merge fmpov