Better handling of namespace validation to fix a number of issues

- Fixes a bug which allows for underscores at the beginning of namespaces: Fixes #1849
- Allows dots and dashes for newer Docker clients: Fixes #1188
- Has the UI display better messaging associated with namespace entry

static/css/core-ui.css

@@ -1479,6 +1479,12 @@ a:focus {
   font-size: 18px;
 }
 
+.co-alert.thin:after {
+  top: 9px;
+  font-size: 13px;
+  left: 19px;
+}
+
 .co-alert-popin-warning {
   margin-left: 10px;
 }

static/css/directives/ui/user-setup.css

@@ -94,4 +94,16 @@
 
 .user-setup-element .user-footer-links a:last-child:after {
     content: "";
+}
+
+.user-setup-element .expandable {
+    height: 0px;
+    transition: height ease-in-out 250ms;
+    margin-top: 16px;
+    margin-bottom: 10px;
+    overflow: hidden;
+}
+
+.user-setup-element .expandable.expanded {
+    height: 60px;
 }