Add "Previous Release" to Launcher Versions

Each time a new Minecraft update is made, there will be servers who take a good amount of time (if at all, e.g. before the changes to combat that 1.9 brought were accepted) to update to it. Some small server admins are simply unable to update it due to being in a place or position they can't log on, or don't have the ability to update it because plugin handlers like Spigot haven't released their new version that's compatible with whatever.

That's why I propose a "Previous Release" installation option for the launcher. It's a simple option given at the top of the version dropdown when making a new installation profile (similar to "Latest Release" or "Latest Snapshot") that will use whatever the release prior to the latest was. This can also be made as a default (in the same way "Latest Snapshot" is when you enable its option; you can't get rid of it) so those who don't have the know-how in making a new installation profile can still switch easier.