removed BuildFlowHelper

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 BuildParametersContextHelper

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 MatrixHelper

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 MavenHelper

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.