removed ScmContextHelper

The ContextHelper classes cause problems with IDE integration because IDEA
does not detect DelegatesTo annotations in delegates. And it is strange
that the first context/closure level uses the helper classes and deeper
levels don't. So they get removed.
removed TriggerContextHelper

The ContextHelper classes cause problems with IDE integration because IDEA
does not detect DelegatesTo annotations in delegates. And it is strange
that the first context/closure level uses the helper classes and deeper
levels don't. So they get removed.
removed PublisherContextHelper

The ContextHelper classes cause problems with IDE integration because IDEA
does not detect DelegatesTo annotations in delegates. And it is strange
that the first context/closure level uses the helper classes and deeper
levels don't. So they get removed.
removed StepContextHelper

The ContextHelper classes cause problems with IDE integration because IDEA
does not detect DelegatesTo annotations in delegates. And it is strange
that the first context/closure level uses the helper classes and deeper
levels don't. So they get removed.
added more @DelegatesTo annotations
removed more context helpers
removed BuildFlowHelper
removed BuildParametersContextHelper
removed MatrixHelper
removed MavenHelper