Add helper for uptime parsing

Parse a UTC-timestamp and calculate the difference to now().
Format the difference in human readable format.
Add detail-routes

Implement routes for bridge- and relay-details, containing full data from
onionoo and parsed human-readable uptime.
Include template-files.
Link to details from results-page

Include links to the respective detail-page from the search-results page.
Add tests for details routes

Implement unit-tests for the details-routes. These are stupidly simple right
now and should be extended on-the-fly once specifications become clear.