AM-92 : Upgrade groovy 2.3.4 -> 2.3.5
Add missing aether dep directly used in our code
Hamcrest isn't used directly (for now)
AM-83 : Fix error message returned when trying to install with --offline an add-on which wasn't previously downloaded
AM-84 : Wrong warning message when trying to uninstall an add-on not installed
AM-85 : Wrong error message when execution describe command of an add-on without existing version (+ display proposed versions in error)
Use error messages too when trying asking for a an add-on with missing --snapshots or --unstable
AM-87 : Add a message when the download of the archive isn't necessary or wanted (--offline)
Unify/Cleanup logs
AM-91 : Skip the version if passed to the uninstall command and display a warning about it