Add log-parser jenkins plugin for better warning/error flags

[patcon]

https://wiki.jenkins-ci.org/display/JENKINS/Log+Parser+Plugin

Would be cool to make the build unstable when drush commands throw non-critical errors, so that we can make it a low-priority to investigate.

Also, might be interesting to force drush make to copy the docroot even when there are errors, and then fail later -- in case other errors in scripting are present, so that they can be accounted for.