rewrite the current style names in pure to be more compatible with css modules

[svnm]

The class names in pure css are not suited to css modules, and could be made much more compact.

[svnm]

Moving this from the README...

It may be something to consider in the future, however would need some discussion with the developers at purecss to ensure they are on board with a new version being written as currently the css source in this module is just a straight copy from purecss 0.6.0 cdn exported as modules for use in components.

It would mean instead of css styleNames like this:

<button styleName='pure-button pure-button-disabled'>A Disabled Button</button>

we could write:

<button styleName='button-disabled'>A Disabled Button</button>

which would obviously be much nicer