Fix auto-documentation link not being updated on version change

As we edit the live model, the fetchCrateDocumentation was not being called as the documentation property of the
model was not undefined annymore.
Bonus feature: Any crate that has a docs.rs link as documentation automatically gets versioning on it

Author: kureuil

app/routes/crate/version.js

@@ -8,7 +8,6 @@ export default Ember.Route.extend({
 
     model(params) {
         const requestedVersion = params.version_num === 'all' ? '' : params.version_num;
-
         const crate = this.modelFor('crate');
         const controller = this.controllerFor(this.routeName);
         const maxVersion = crate.get('max_version');
@@ -36,7 +35,8 @@ export default Ember.Route.extend({
         };
 
         const fetchCrateDocumentation = () => {
-            if (!crate.get('documentation')) {
+            if (!crate.get('documentation') ||
+                crate.get('documentation').substr(0, 16) === 'https://docs.rs/') {
                 let crateName = crate.get('name');
                 let crateVersion = params.version_num;
                 ajax(`https://docs.rs/crate/${crateName}/${crateVersion}/builds.json`)