Bump gds-api-adapters to 14.1.0

This picks up the Content Store adapter.
Limit width of Manual and Document summaries

This commit limits the width of Manual and Document summaries in order
to bring it in line with the rest of the body content in Documents.

This also fixes an issue with the bug fix for line width on content in
the body. It does this by using the CSS not selector to go through all
children except h2s, so it will never skip the first element in
.govspeak, which might be a h2.
Merge pull request #68 from alphagov/limit-width-of-summary

Limit width of Manual and Document summaries
Merge pull request #69 from alphagov/bump-gds-api-adapters

Bump gds-api-adapters to 14.1.0
Fix for collapsible sections width issue

With the fix introduced in #68, there was an issue were it was finding
the first element which wasn't a h2, when it should have been starting
at the first element and doing nothing if it was a h2. This commit fixes
that bug.

Also testing the headerlessContent function.
Merge pull request #70 from alphagov/fix-for-collapsible-manuals-width-issue

Fix for collapsible sections width issue
Remove unnecessary 'selenium-webdriver'

The cucumber features use Poltergeist for javascript execution.