Index information included in the POM file

[bhermann]

As part of the Maven Crawl process, it would be interesting to add information from the POM file to the index, so users can search for artifacts based on the information provided there.

Specifically, the textual information (name, description) would be helpful to support search queries on domain concepts.

URLs leading to other systems could also be added to aid research that is using information from source control or issue tracking systems.

Dependency information might be interesting to be able to resolve necessary libraries or to query for them.

See https://maven.apache.org/pom.html for more inspiration.

[johannesduesing]

Create a new prototype from scratch that only mines metadata (for now)