Completed Releases

It would be nice once a release's status has been updated to "Released" to not include it in the option in the edit modal dropdown, alternatively maybe applying a "Completed" flag to the release could handle this.

We've only been using Freshrelease for about 2 months and at the moment we already have 13 releases. This list is going to become much larger over time. 

When we release a new version of our application, we package everything up, publish and rollout our new code, at this time we flag the release to "Released" in freshrelease at this point we will never be adding new cards to this release and don't need them to appear in the dropdown list.

It would also be nice to have a filter on the releases page to toggle between Released and Unreleased.