Redesign: replacing current project tiles with new ones from figma mockup

Currently project tiles require you click in to a modal, we've redesigned them with a call to action button and added a active tag.

Old:

New:

## Details:

* We will need a short description for each project. Let's be sure to check the description with the project.
* This might be a good time to check in to see which projects should be featured on the tiles.
* We might also want consider how many tiles we'd like on the page. Let's start with eight or less and go from there.
* "Read More" buttons should lead to project page.
* For example: the "read more" button for Choose Native Plants PA would lead you to https://codeforphilly.org/projects/pa_wildflower_selector
* Lets add direct links for github, and project website on each tile, similar to Hack for LA, and test it out on some users?

まず、既存の project-tile のエントリーポイントを特定し、Figma のモックアップと比較します。再設計したタイルを実装してテストする前に、プロジェクトの説明、注目プロジェクトのリスト、タイルの数、Read More の遷移先、GitHub とプロジェクトウェブサイトへの直接リンクを確認します。

索引モデルが issue の本文から書いたものです。