Moves TabsView into jck-library-extensions.

Squashed commit of the following:

commit 927d4f1a23b4b15709358ed8007f868c7c823748
Author: Jeremy Kahn <jeremyckahn@gmail.com>
Date:   Sat Jun 7 17:15:51 2014 -0500

    Moves TabsView to jck-library-extensions.

commit 8771460347583d3203050d5a5eca47d752904ba5
Author: Jeremy Kahn <jeremyckahn@gmail.com>
Date:   Sat Jun 7 16:43:44 2014 -0500

    Refactors tabs.js, adds jck-library-extensions.
Integrates Sass, compresses production CSS.

Squashed commit of the following:

commit 68706a01c90be6bb4d3f4e1bf07f21d0c7db0586
Author: Jeremy Kahn <jeremyckahn@gmail.com>
Date:   Sun Jun 8 17:25:51 2014 -0500

    Bumps to 0.4.10.

commit 04477f4a7b6377f2bda0d428e72cbc3841675a03
Author: Jeremy Kahn <jeremyckahn@gmail.com>
Date:   Sun Jun 8 17:25:09 2014 -0500

    Tweaks <select> background.

commit 36ad883b410b113487f36caa017cb093617fb9ad
Author: Jeremy Kahn <jeremyckahn@gmail.com>
Date:   Sun Jun 8 17:13:24 2014 -0500

    Improves Compass development and production tasks.

commit 8810a6aea7d8dec1760b39d0c4845b93dabb4be6
Author: Jeremy Kahn <jeremyckahn@gmail.com>
Date:   Sun Jun 8 17:04:34 2014 -0500

    Compresses generated CSS.

commit 982584c23caf8bc642126a83f91b67ad947ea849
Author: Jeremy Kahn <jeremyckahn@gmail.com>
Date:   Sun Jun 8 12:15:04 2014 -0500

    First-pass at Sass/Compass integration.
Merge branch 'master' into gh-pages