Fix url view helpers for root page links

When a module provides a hierarchy of routes (not just a single
one) and you link from the root page to the root page, the ensemble
helpers request a route <id>/ instead of just <id>. The fix checks
for this scenario and proxies the url request to the view helper
with the <id> route name.
Merge pull request #4 from ensemble/hotfix/url-helper

Fix url view helpers for root page links