Update to joda-time 2.6
Update junit to 4.12
Update mockito-all to 1.10.17
Update credentials dependency to 1.19
Update to git-client-plugin 1.13.0 - CVE-2014-9390

Refer to http://article.gmane.org/gmane.linux.kernel/1853266 for a
description of the client side bug which is resolved by JGit 3.5.3.

It seems unlikely the client side bug will affect many Jenkins users
due to the relatively limited workflow used in the git client plugin
and the git plugin.
Update mailer dependency to 1.12
Revert "Update mailer dependency to 1.12"

This reverts commit d9811ba1b2bf0108bf94e3680b01599cb73cadad.