Tidy layout of team page

The team page was a bit of a mess:

- invited and active tables didn’t line up
- lots of things were wrapping onto two lines
- the empty fields for when a user didn’t have permissions looked broken

This commit splits each row of the table (not actually a table any more)
onto two lines. First line has the user’s info, second has their
permissions and any associated actions.

app/assets/stylesheets/views/users.scss

@@ -0,0 +1,16 @@
+.user-list {
+
+  @include core-16;
+
+  &-item {
+
+    padding: $gutter-half 0;
+    border-top: 1px solid $border-colour;
+
+    &:last-child {
+      border-bottom: 1px solid $border-colour;
+    }
+
+  }
+
+}