Updates to javadoc and comments.

Signed-off-by: Anders Hammar <anders@hammar.net>
[JENKINS-21063] Indicate in icon (or tooltip) if a release build failed.

Failed release build is now indicated in badge/icon as well as tooltip. Also reworked dryrun badge to align.

Signed-off-by: Anders Hammar <anders@hammar.net>
[JENKINS-21063] Badge now retrieves dryRun, version, and failedBuild info from build instead of storing it.

As a side effect, variables in M2ReleaseBadgeAction were removed which will affect builds persisted with older versions of the plugin.
Also, required version of Jenkins was bumped to 1.509.3.

Signed-off-by: Anders Hammar <anders@hammar.net>
[JENKINS-21063] Changed failed badge to indicate uncertainty wrt release and fixed backwards campatibility for builds by old versions of plugin.

Signed-off-by: Anders Hammar <anders@hammar.net>
Merge remote-tracking branch 'upstream/master' into JENKINS-21063

* upstream/master:
  ReleasesCauses are now userIdCause - so update RSS appropriatly.
  [maven-release-plugin] prepare for next development iteration
  [maven-release-plugin] prepare release m2release-0.13.0
  Fixed a few UI text items in the project configuration dialog to align with text items in release dialog.
  [FIXED JENKINS-20983] Improve help text for "Preselect append Jenkins username" option
  [FIXED JENKINS-21060] Improve help text of "Number of successful release builds to keep"