moved tests from core.helpers to core.util, removed core.helpers package, replaced individual static imports with .* imports

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1595195 13f79535-47bb-0310-9956-ffa450edef68
javadoc fix

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1595201 13f79535-47bb-0310-9956-ffa450edef68