Display homepage links when no results are found.

Closes # 486.

- Added localization for text on no results page.

- Renamed link from “Clearing all search filters” to “Browsing all
locations” because I think it’s the better message in this context.
Hence, I also removed the “x” icon.

- Added spec to check for the homepage links on no results page.
Merge pull request #539 from codeforamerica/486-links-for-no-results

Display homepage links when no results are found.