[cleanup] Fixed checkstyle errors
Issue #348: Enforce the presence of license headers in all the files
Added missing license headers
Issue #126: Enable the Clirr plugin in the build
Issue #348: Enforce the presence of license headers in all the files
Issue #353: Enable the Checkstyle plugin in the build
Done.
Issue #348: Enforce the presence of license headers in all the files
Also check POMs