prettify the readme with some graphics

made the top image actually clickable so the download buttons "works".
fixes #132 - style configuration.
Merge pull request #114 from google/imagified-readme

prettify the readme with some graphics
readme - link download to releases page and not a specific release
Move `Contributing` guide to a CONTRIBUTIN.md file

So it shows up as a notice when people open issues/PRs

https://github.com/blog/1184-contributing-guidelines
Merge pull request #151 from google/contributing-md

Move Contributing guide to a CONTRIBUTING.md file
Adds missing closing section tag around highlights.
Merge pull request #152 from jbnicolai/missing-closing-section

Adds missing closing section tag around highlights.
Fixes indentation and removes duplicate newlines.
Merge pull request #154 from jbnicolai/fix-indentation-styleguide-index

Fixes indentation and removes duplicate newlines.
readme - remove features text

It's all covered in the above image.
Targeting *:before and *:after for box sizing
update indent value of jshint config and follow style rule.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>
Merge pull request #161 from appleboy/patch

update indent value of jshint config and follow style rule.
Merge pull request #153 from google/readme-remove-features-text

readme - remove features text
Merge pull request #158 from Charca/box-sizing-fix

Targeting *:before and *:after for box sizing
Fixes #103  grid issues (ty @CreativeJuiz)
Close GH-85: A bunch of (smaller) changes….
revert manifest.webapp version change in #85
Update gitignore

Insert final newline to match guidelines.