Cleans styles on news/blog home

- Styles pagination
- Removes space before period in date
- Cleans up styles for subscribe
- Adds 'back to 18F home' link
- Adds 'back to full blog list' link to tag filter page
- Standardizes how we display 'continue reading post'
- Aligns text baseline of blog snippets with baseline of meta info

Closes #438

## Top of page
![screenshot 2014-12-24 14 06 52](https://cloud.githubusercontent.com/assets/4827522/5551062/66ba7b8a-8b76-11e4-87fb-8f724afdba10.png)

## Bottom of page
![screenshot 2014-12-24 14 07 12](https://cloud.githubusercontent.com/assets/4827522/5551061/66b8f36e-8b76-11e4-91d0-1578dc5f950f.png)