Fixed bug in authenticate for bash open and added Delete functionality

Ok, so this PR fixes a bug around https://github.com/dekz/flickr-store/pull/new/delete#L1R25. It seems in my combination of OS and shell the `open` command was interpreting the `&` and backgrounding the task, then executing `perms=delete`. This is a problem because the default permissions then don't include `delete`. Which makes implementing delete functionality suck. So I fixed that, then added delete functionality.