Speed up maven site

Maven site generates a lot of dependency reports by default. Removing
some extraneous information speeds up `mvn site` by about 2 times.

Also fixes some "Artifact X has no file." errors; cf.
http://jira.codehaus.org/browse/MPIR-251
DDF-25: Remove nonexistent dependencies from poms

A few poms list dependencies that do not exist, which causes warnings
and delays with mvn site.