First cut at social media icons

TODO

- Design
- Agreement on canonicalUrl implementation (ie. no editions)
- Sharing on galleries & videos
- Working tests
Working tests for each of the four social networks
Using canonicalUrl across articles, gallery, video pages
Typo
Wrapped all s
Style via Jim
Fresh text fixtures
Remove standfirst from fragment

LinkedIn does a good job of fetching this from the URL we give it.
Hide social icons behind a switch
Merge branch 'master' of github.com:guardian/frontend into share

Conflicts:
	common/app/conf/switches.scala
Merge pull request #513 from guardian/story

Wrapped all timeline content standfirsts in links
Remove println
Fixed typo causing timeline js issues
CSS tweaks to icons
Merge pull request #514 from guardian/story

Fixed typo causing timeline js issues
Remove outer div & added common social-network class
Merge pull request #493 from guardian/share

Share buttons
Default social switch to off
Merge branch 'share'
Merge branch 'master' of github.com:guardian/frontend into play-release