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
Specify font stacks for grids and grid units

By setting _specific_ font stacks grids, it can be assured that the
letter and word spacing will be applied correctly. The font stack for
grid units is then set back to `sans-serif`, which is also the default
font stack that Normalize.css applied to the `body`.

Closes #41
Added unminifed roll-up of everything. 'pure.css'.
Update font-stack with recent findings

Based on conversations in https://github.com/yui/pure/issues/41/,
this font stack was updated with more fonts to fully cover all
target environments where grids were breaking.
update HISTORY.md with #41 fix
Merge pull request #2 from tilomitra/grids-fonts

Update font-stack with recent findings
Merge branch 'grids-fonts'

Conflicts:
	HISTORY.md
De-cruft and improve Responsive Grids manual test page
Add custom font section to Responsive Grids manual test page
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