This commit improves the dependency mapping infrastructure to include the
groupId and artifactId attributes alongside the existing version. For
consistency, the attribute has been renamed from `versions` to
`mappings`.
This allows to better support the `redis` use case: the starter was
renamed from `spring-boot-starter-redis` to
`spring-boot-starter-data-redis` and previously we had two entries
excluding each other using version ranges.
Closes gh-219
This commit splits the feature of Spring Initializr in several modules:
* `initializr-generator` is a standalone library that is responsible for
generating projects based on a `File` directory. It has a minimal set of
dependencies and is not web-related
* `initializr-web` provides the web integration (project generation,
meta-data, etc)
* `initializr-actuator` is an optional module that can be added to
support project-generation-specific statistics
Closes gh-214
