* Allow for requirements to be added to a project. The requirements
will determine what needs to be measured later on.
* Introduce a abstract version control system class with `Subversion` and `Git`
as concrete instances.
* Use metric source id mapping to find teams in the Wiki.
* Allow for adding a default team to a Jenkins instance. The default team is
responsible for all jobs that have not explicitly been assigned to a team.
* Bug fix: if a product or team has a target or low target of 0 specified in
the project definition, don't ignore it.