Lock summary fields when appropriate

Match the rest of the form
Upgrade capybara to 2.4.4

https://github.com/jnicklas/capybara/blob/master/History.md
Create test for asserting all fields are disabled

* When adding new fields it’s common to forget to disable them in
archive and preview, create a helper to apply a test to each edition
format
Test all fields disabled on business support

* Test all form fields for disabled-ness
* Fix business areas which weren’t disabled
Test and disable campaign fields
Add disabled field tests to remaining formats

* Fix missing disabled fields on licences and videos
Merge pull request #303 from alphagov/fix-disabled-summary-fields

Disable all fields on published editions