FLUME-3280 Improve maven build to help code reviews by adding static …

…code analyzer

Adding spotbugs, pmd to the build.
moving flume-checkstyle to a new build-support module that contains
any future build tool configuration.

Fixed some trivial checkstyle issues.

Updated apache parent version and maven plugin versions.
Added maxAllowedViolations so this commit could contain only the new checks
and not any code change.

Did some cleanup in the pom files.

This closes #232

Reviewers: Peter Turcsanyi, Endre Major

(Ferenc Szabo via Ferenc Szabo)