new interpolator so the one from 2.0 was used and some envar handling was back ported. Unit tests
have been added for envar handling as well as an IT. The maven-core-it script will now set
an envar which is used in it0090.
git-svn-id: https://svn.apache.org/repos/asf/maven/components/trunk@368108 13f79535-47bb-0310-9956-ffa450edef68