Added center elbows.
Refactored how columns work in general:
 - Columns are 100% of their parent element
 - The lcars-column-inner element in the column (required in all columns) will be the total height minus the appropriate elbow heights.

Signed-off-by: Martin Evans <martindevans@gmail.com>
Merge branch 'master' into feature/center-elbows

Conflicts:
	index.html
	src/less/lcars-variables.less
Merge pull request #13 from martindevans/feature/center-elbows

Added center elbows.