promote vss to proper antlibs

git-svn-id: https://svn.apache.org/repos/asf/ant/antlibs/vss/trunk@991765 13f79535-47bb-0310-9956-ffa450edef68
tree: 3f25efcde19b84e883483f17b479313fd6dc22d7
  1. NOTICE
  2. build.xml
  3. docs/
  4. src/