Merge pull request #1502 from darxriggs/master

fix Javadoc
cleanup - make pom.xml files more consistent
Merge pull request #1504 from darxriggs/maven-pom-cleanup

cleanup - make pom.xml files more consistent
[JENKINS-24380] Linking to Wiki from log message too.
Added assertion as suggested in JENKINS-22767.
[FIXED JENKINS-26201] Noting 47fa17b, misattributed to an unrelated issue.
installIfNecessaryFrom Javadoc improvements and nullness annotations.
JUnit 4.
[FIXED JENKINS-26196] More robust handling of server errors in FilePath.installIfNecessaryFrom.
s/XXX/TODO/
Javadoc updates.
Throwable.printStackTrace() to stderr is gratuitous when we are sending the exception to Logger.