[maven-release-plugin] prepare for next development iteration
support delivery pipeline view as the default view

The XHR calls to the delivery pipeline view api do not work
when the view is the default view; this is due to the use of
'api/json' as the api url.  The root level
`http://server/[JenkinsRootUrl]/api/json` URL is reserved
for the JSON API for jobs entities.

This patch forces the XHR calls to use the absolute URL to
the JSON API for the pipeline view, regarldess of
the request URL.

Also includes small reorganization of the embedded Javascript in
main.jelly for readability and eventual use of closures for
best practice variable scoping.
Updated README
Added -Djava.awt.headless when executing unittests
JENKINS-21123 TokenMacro for PIPELINE_VERSION
Merge pull request #67 from steve-jansen/default-view-support

Fixes JENKINS-23282: support delivery pipeline view as the default view
JENKINS-23353: fixes creating new jobs from the default view

avoids a stack overflow exception when creating a new job from the default view
when a Delivery Pipeline view is configure as the default system view
Merge pull request #68 from steve-jansen/default-view-support

JENKINS-23353: fixes creating new jobs from the default view
JENKINS-23372 Plugin is incompatible with Build Pipeline Plugin 1.4.3 manual triggers fixed.
Constructor for BuildPipelineView has changed.
JENKINS-23373 rename or delete of jobs fails when just regexp is configured
[maven-release-plugin] prepare release delivery-pipeline-plugin-0.8.1
Merge version 0.8.1 into pipeline-runtime
use jenkins root url from configuration