Improve saved search email layout [MJ-750]

Displays company logos, company names, job locations, and total job counts in saved search emails. Company information is not available in the rss feed, so we transparently use the json feed if a saved search appears to have been made from a microsite (has 'feed/rss' in the feed url).

Attached is a more recent screenshot of a saved search digest as viewed on a mobile device. Desktop viewing is unchanged from the most recent shot posted on Jira.

![screenshot_2014-02-27-09-22-09](https://f.cloud.github.com/assets/3379265/2286191/766385ec-9fde-11e3-80b9-6e0493242dc9.png)

All tests pass.