enhc Created layout of main navigation

Setup the layout part of main navigation, have not dealt with type
treatment yet.

Added sass component and globals folder, components to store all sass
modules and globals for global variables.

Added a util file for general utilities like clears, floats, etc. Added
an umarked list style there.

TODO: probably don't need a separate folder for globals, just one file.

Other changes:
- Setup grid settings as per Neat setup instructions:
github.com/thoughtbot/neat
- Fixed some whitespace issues.
Using jinja var for donate page link

As mentioned by @cmc333333
Merge pull request #43 from msecret/enhance-top_main_nav

Created layout of main navigation