add ls-pie icon
server side /stats rendering
render stats pie chart on the client

chart library works on canvas element with `data-stats` property set
workaround for an invalid component/chart

use master instead of released version
add per tag stats

/stats/{tag} - displays stats for a specific tag
link to the stats is now displayed in the footer

improve tag handling in request - app.param us used to insert tag
related data into request and response objects
Merge remote-tracking branch 'origin/stats'