Upgrade to Rails 4.1.9

Upgrade the Rails gem to 4.1.9.  Rails behavior changed in version 4.1.2, requiring that we avoid using slashes in arguments to path helpers.  This MR changes routing to use nested resources for that reason.

TODO:

* [x] Make Spinach tests green
* [x] Make it mergeable

cc @sytse @dzaporozhets

See merge request !1494