Update jquery-rails gem

As of jquery-rails 3.0.0, jquery-ui is no longer included. It's
available through the jquery-ui-rails gem. There is still a custom
build of jquery-ui in the codebase which could be replaced by
appropriate requires from jquery-ui-rails.

The version bump takes us to jQuery 1.10, which no longer has the
.live() method so the remaining uses of it have been replaced with calls
to .on().
Fix chosen-select behaviour for single selects

The update to jquery had broken this behaviour slightly, resulting in
single selects not being updated properly.

Also remove redundant select_from_chzn helper and replace with calls to
select_from_chosen.
Fix some jQuery compatability issues

- Calling $('select').val('') now sets no value rather than returning to
  the default value, so we need to be explicit that we want to revert to
  English.
- The selector $('input[value!=""]') now matches the original value of
  the input, not the current value. Instead, filter the list of inputs
  looking for non empty values.
Update cucumber-rails gem
Remove router-client gem and router gem group
Update carrierwave gem
Fix thumbnail URL issues from carrierwave upgrade

- Handle nil source argument in path_to_image
- Use #thumbnail.url instead of #url(:thumbnail)
Upgrade delayed_job gem to 4.0.0

Required for Rails 4 compatibility
Merge pull request #1193 from alphagov/pre-rails-4-gem-upgrades

Gem upgrades (and removal)

https://www.pivotaltracker.com/story/show/63292484