Set up publication of PR final artifacts to artifactory-online.

This setup is dependent on a $typesafeArtifactoryPasswe environment
variable being passed at build ot builders, using the Jenkins Mask
Passwords plugin:

https://wiki.jenkins-ci.org/display/JENKINS/Mask+Passwords+Plugin
fix artifactory publishing

 - directory for maven artifacts is `dists/maven/latest`
 - the xml for the settings file was wrong, and password masking unwieldy,
   so decided to simply update the ~jenkins/.m2/settings.xml file on the build slaves
Merge pull request #4 from adriaanm/artifactory-publish

Artifactory publish