Added spec element to GhprbTrigger.

By default, the GhprbTrigger XML element generated does not contain a <spec> element. When this element is not present, Jenkins will not use the trigger (tested with Jenkins v1.565, Git client plugin v1.9.1, Git plugin v2.2.1, Github API plugin v1.44, Github Authentication plugin v0.16, Github plugin v1.8, Github Pull Request Builder plugin v1.12).

By default, the spec element seems to get the same value as the cron element (when configured manually).
Merge pull request #211 from eveoh/pullrequestbuilder-spec-fix

Added spec element to GhprbTrigger.
[JENKINS-22087] Add job dsl support for RundeckNotifier plugin

add RundeckContext and modify PublisherContext to support the RundeckNotifier directly in the job dsl
fixing default values in RundeckContext
adding code to correctly collect and join the options and nodeFilters
making sure that the jobId can't be null or empty in the PublisherContext so that it can't be bypassed
fixing test assertion to correctly assert empty value() instead of attributes()
making it explicit where the xml for the RundeckNotifier comes from in the job config xml
make it so options and nodeFilters can be called multiple times just like option and nodeFilter
[JENKINS-22087] Add job dsl support for RundeckNotifier plugin

updating the documentation
[JENKINS-22087] Add job dsl support for RundeckNotifier plugin

updated release notes
[JENKINS-22087] Add job dsl support for RundeckNotifier plugin

updating documentation to be in line with existing documentation format
adding examples of usage
Added a buildName wrapper, for Build Name Setter plugin
use CentOS box, it is not possible to install older Jenkins versions with apt-get
fixed typo
cleanup, added release notes
Merge branch 'feature/build-name-setter'
cleanup
Merge branch 'JENKINS-22087'

Conflicts:
	docs/Home.md
Add support for new version of build timeout plugin
Add support for new version of build timeout plugin
Added deprecation warning
Check minimum Plugin Version.
Added extra deprecation warning and extended the migration guide.