Add .gitignore

Ignore Mac OS X .DS_Store
Add node_modules to .gitignore

Add node_modules to global ignore as well as directory/per project
ignore.
Add build tools

- Add .bowerrc; set `/ui/vendor/` as default path
- Add bower.json; add jquery, normalize-css
- Add package.json; add grunt tasks for clean, concat, sass, jshint,
  watch