Extract common Jenkinsfile logic into Pipeline Global Library

[vdice]

This repo's Jenkinsfile as well as the controller-sdk-go repo's Jenkinsfile share common logic, especially as of https://github.com/deis/controller-sdk-go/pull/46 which builds workflow-cli in place, duplicating many steps used in this repo's pipeline.

It would be preferable if we extracted shared logic into common functionality via the Pipeline Global Library to both reduce duplication and enable only making changes to such functionality in one location. Some functionality will even prove to be generally useful outside of workflow-cli/controller-sdk-go's scope, such as sending email notifications on e2e failures.

[vdice]

A first attempt at following the resources mentioned in the description didn't pan out very well, but it looks like there has been more activity on https://issues.jenkins-ci.org/browse/JENKINS-31155 which might be useful when this is pulled in.

[mboersma]

Also there's https://github.com/jenkinsci/workflow-remote-loader-plugin which might help.

[Cryptophobia]

This issue was moved to teamhephy/workflow-cli#24