Generate a release with the required jars instead of build upon install

[jujusb]

We should avoid as much as possible to checkout source code and build upon install. For own services it is ok during development but external dependencies may break and installation if a breaking changes is introduced in the external dependency.
The idea is to fork / create a repo that builds and generate a release with the required jars that are downloaded here (checking the SHASUMS) for the theme and the LTI plugin