Version Selector (#4386)

* Show current version of docs in nav

* Branch in edit link

* WIP version selector

* An actual working but not pretty version dropdown

* update URLs for versions

v1.7: https://kubernetes.io/docs/home/
v1.6: https://v1-6.docs.kubernetes.io/docs/home/
v1.5: https://v1-5.docs.kubernetes.io/docs/home/
v1.4: https://v1-4.docs.kubernetes.io/docs/home/

* fix v1.4 and v1.5 paths

* Tidier drop downs

* Make font visible always

* Make background match main nav always

* change to major.minor version number

* show only major.minor version in drop down list

* switch from githubbranch to docsbranch

* update githubbranch

* update githubbranch values

* Border radius for bottom of dropdown

* Tabs are hard

editdocs.md

@@ -12,7 +12,7 @@ $( document ).ready(function() {
         $("#generalInstructions").hide();
         $("#continueEdit").show();
         $("#continueEditButton").text("Edit " + forwarding);
-        $("#continueEditButton").attr("href", "https://github.com/kubernetes/kubernetes.github.io/edit/master/" + forwarding)
+        $("#continueEditButton").attr("href", "https://github.com/kubernetes/kubernetes.github.io/edit/{{ page.docsbranch }}/" + forwarding)
         $("#viewOnGithubButton").text("View " + forwarding + " on GitHub");
         $("#viewOnGithubButton").attr("href", "https://git.k8s.io/kubernetes.github.io/" + forwarding)
     } else {