Root Module metadata is incomplete.

[NicolasRouquette]

I noticed that for both ivy & sbt reports, the metadata about the root Module is incomplete; in particular, there is no license information.

For Ivy reports, the root module is constructed with only a ModuleID:

https://github.com/jrudolph/sbt-dependency-graph/blob/master/src/main/scala/net/virtualvoid/sbt/graph/backend/IvyReport.scala#L50

For sbt reports, the root module is also constructed with only a ModuleID:

https://github.com/jrudolph/sbt-dependency-graph/blob/master/src/main/scala/net/virtualvoid/sbt/graph/backend/SbtUpdateReport.scala#L48

It is unclear how the additional metadata (license, extraInfo, ..) could be passed to these constructors.