CYB-368 - Gallery: browser back button in item detail view doesn't return to gallery main

https://jira.ets.berkeley.edu/jira/browse/CYB-368
@nicolaasmatthijs this is for when you click on an author's name in the comment. Generally, you should be able to do a `grep` for everything before the `:` - `/canvas/embedded/gallery/author/`. 

See https://github.com/christianv/datacultures/commit/fb7684fd818a7da0856644e2d8e9e81ee627ec2b#diff-016d4541baec6d0f5fbc9a99ae24774eR31