Add transpile task and switch entry points to ES5 output

[i-like-robots]

• Moves all modules into src folder
• Added task to transpile contents of the src folder to a dist folder
• Adjusted Bower and NPM entry points to transpiled modules
• Added prepublish hook to package manifest

[ironsidevsquincy]

Anything we can do with bower to mean we don't check in dist? Some sort of pre-tag git hook?

[i-like-robots]

Looking into that ATM - there's always the option to upload a zip with a release which I assume Bower will pick up =/

[i-like-robots]

Or we simply no longer publish on Bower... the lazy loading code could be moved into n-ui? But I suppose we wouldn't be able to apply the same rule to each component.

[i-like-robots]

Tested on front page and looking 👌

[i-like-robots]

Beta released https://github.com/Financial-Times/n-image/tree/v4.3.0-beta.2

Seems to work just fine for front page