[FIXED JENKINS-24317] Corrected user dir migration code from JENKINS-23872.
Adapted from #1375 by @daniel-beck: omitting change to User construction, and adding test.
(cherry picked from commit 088edabb31a90cd607f3c6a3123effce5703c817)

Conflicts:
	changelog.html
[FIXED JENKINS-24316] Fixed unknown task icon src path construction

(cherry picked from commit 286337ea39c0db6e056af61e616736bafc5f0581)
Readd static resource path for task icons [JENKINS-24316]

Missed this in previous commit - bad idea making even small changes late at night ;)

(cherry picked from commit 3daa6a97b02635d672e7646e83edb93abf50db06)
[maven-release-plugin] prepare release jenkins-1.577
[maven-release-plugin] prepare for next development iteration
updated changelog for release
updated changelog as a part of the release
merged back the RC branch

Conflicts:
	changelog.html