icebox/views:

Removed an obsolete TODO comment.
icebox/views:

For consistency and convention, append slashes to all generated URLs.
icebox/tests:

Updated a handful of tests to expect trailing slashes in the URLs
sent back in view responses.
icebox/icebox_api.md:

Added trailing slashes to all method URLs, for consistency and
convention.
icebox/icebox_api.md:

Added API doc for the two new artifact group methods.