To achieve that, this PR
- converts static/index.html ("console") and graph to templates
- moved the handlebars template to separated file to avoid escaping issues
Route changes:
/status -> /
/static -> /console
/static/graph.html -> /graph
This roughly comprises the following changes:
- index target pools by job instead of scrape interval
- make targets within a pool exchangable while preserving existing
health state for targets
- allow exchanging targets via HTTP API (PUT)
- show target lists in /status (experimental, for own debug use)