Allow keys with dashes in web UI

Allow dashes in key names and still be able to view and modify them using the web UI.

URL:s will now look like this:

    http://localhost:8500/ui/#/dc1/kv/
    http://localhost:8500/ui/#/dc1/kv/folder/
    http://localhost:8500/ui/#/dc1/kv/folder/key-with-dashes
    http://localhost:8500/ui/#/dc1/kv/folder/key-with-dashes/edit

This will resolve hashicorp/consul#109.