Film Awards - banner on container page [#IDN-1693]

Created by Lisa Villani.

https://jira.gutools.co.uk/browse/IDN-1693
Fix CSS source-style issues noted by @kaelig

https://github.com/guardian/frontend/pull/2772#discussion_r8893720
https://github.com/guardian/frontend/pull/2772#discussion_r8893721
Use optimised version of the banner provided by @kaelig

https://github.com/guardian/frontend/pull/2772#issuecomment-32358503

Whatever tool @kaelig's using seems to do better than pngcrush...
Merge pull request #2772 from guardian/film-awards-banner

Film Awards - banner on container page [#IDN-1693]