Fix a couple of Ajax related path issues

  - Include context path when generating page specific JS
  - Include context path when making Ajax requests
  - Fix Ajax path matching (previously renderVersion was being set to
    "ajax")
Add lift.getPageId function
Rename ajaxServer to contextPath
Fix pattern match (again!)
Adjust pattern match for consistency
Include context path in liftPath
Add Scaladoc and rename liftUriPath
Merge pull request #1597 from lift/pmb_ajax

Fix a couple of Ajax related path issues