[FIXED-HUDSON-7162]

Hudson ignores Maven pom.xml path when it is specified as absolute path.
Provided utility methods for checking whether a path is absolute and
absolutizing a given path (w.r.t. a base).
Provided a unit test case for this scenario (@Bug 7261).



git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@34004 71c3de6d-444a-0410-be80-ed276b4c234a