Added accessor methods to chartLayout

The accessors means that we don't have to expose the structure
I've also added a class to the chartArea, having a 'g' selector felt a bit dangerous!
Added callback properties for components so that consumers don't need to conform to a particular data model.
Merge branch 'master' of https://github.com/ScottLogic/d3-financial-components
Merge pull request #104 from ColinEberhardt/master

Added accessor methods to chartLayout
Fixed code style issues
Added containers for axes and a chart background
plotArea background now has correct z-index

Fixed JSHint issues (and for other components)
Build now runs JSHint!
Merge pull request #106 from ColinEberhardt/master

Adds axis containers and chart background.

Merged so I can pull the changes into the large fork I currently have of the gh-pages branch
The examples are no more....
Updated as per pull request comments
Merge pull request #107 from tunerscafe/master

Guessing there's no more comments so merging
Removed nearly 1000 jshint errors and rebuilt dist.
Merge pull request #111 from tunerscafe/master

Removed nearly 1000 jshint errors and rebuilt dist.