Remove Normalize.css from `src/`, it's a dependency not Pure source code

This also removes `forms-core.css` which was effectively Normalize.css'
form related styles prefixed with `.pure-form`.
Update npm dependencies
Lock down the version of Normalize.css to 1.1.2
Simplify Grunt tasks and include Normalize.css import by default

Running `grunt` will now use Bower to install Normalize.css. As of 1.0.0
Bower got much faster, and it also uses a cache so the install only
happens once.

Added `grunt build` which does not the "import" or "test" tasks.
Tweak formatting and remove unused stuff in Gruntfile
Use bower.json to get current Normalize.css version number
Added unminifed roll-up of everything. 'pure.css'.
Merge branch 'master' of github.com:omeid/pure into omeid-master
Create non-minified pure-nr.css file along with pure.css
Update README and HISTORY for new non-minified rollup files
Merge branch 'grunt-bower' of github.com:ericf/pure into ericf-grunt-bower
Update HISTORY for Grunt + Bower change and Base module requirement