Use Capybrara 1.1 for poltergeist compatibility

https://github.com/jonleighton/poltergeist/pull/208 details incompatibility between Capybara 2 and Poltergeist.
Add edit and update actions to editions controller
Add edit edition feature
Fix slug generation js
Add govspeak help and remove static jquery template

This change involves copying a library and a partial from publisher which feels wrong.
Possibly something to review in future, duplicate code is bad.
Add remove part button
Fix broken partial path
Fix edit link method name typo
Fix jquery-rails gem at 2.0.2 for bootstrap compatibility
Use helper method to set up parts like publisher
Enable sortable parts
Set an initial title when creating new Editions
Turn off auto-opening the first part
Add title and search description fields
Format flash messages, don't redirect in error.
Reword commented failing scenario assertions
Use released version of govuk_content_models
Add before_filter for country and edition lookup
Add pending message to failing assertion
Make textarea font color consistent with form