Allow selecting up to date Leiningen versions #2732
Description
Currently the Leiningen versions that are available to select from are hard-coded into Cursive. That means that if I forget to update them, or someone is using an old version of Cursive, they cannot access current versions. The hard-coded list should be updated automatically as part of the build process, and it should also be occasionally dynamically checked by the running IDE to allow use of newer versions.