Revert "Consecutive trailblocks have a line between them - fixes #948"

This reverts commit b94f2dca52f23e8581a1f1603f881959eec415f6.
Revert "Nav popup is positionned correctly"

This reverts commit 1793cf47af1019bc9a340804634dc60cb8b0b514.
Revert "Fix tests"

This reverts commit baf3b37e64797d01bac225468499673a18902e5d.
Revert "Merge pull request #941 from guardian/griddle-redux"

This reverts commit 9317b727b12b416f0fa2d717d0b2e4ee5bc4e166, reversing
changes made to 0e648862e464ce8865a5b008b55cd98505e8112d.

Conflicts:
	common/app/assets/javascripts/modules/trailblock-show-more.js
	common/app/assets/stylesheets/global.scss
	common/app/assets/stylesheets/head.scss