do not allow colon inside a PHPCR route uri

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | yes (we do not allow namespaced nodenames anymore)
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | https://github.com/symfony-cmf/RoutingBundle/issues/259
| License       | MIT
| Doc PR        | -