Add rTorrent third party exporter

Fix wrong exposition format example

And also use seconds instead of milliseconds.

Add InfluxDB exporter

Fix config key typo

Fixes prometheus/alertmanager#274

Add ruby link to pushgateway section

Fix Slack send_resolved default

Add Ubiquiti UniFi third party exporter

Fix typo in AM client docs

Add blog post about Alertmanager templating

Merge in changes for 0.17.0

Update docs for new java client, and other changes.

Remove wrong scrape_timeout from getting started examples

Scrape timeout can't be higher than scrape interval, so this config is
just wrong. This change remove all mentions of the timeout, we chose a
reasonable default, if a user has different needs they can find it in
the configuration docs.

Remove misleading hints about multiple evaluation_interval

There is only one global evaluation_interval at this time, so a "by
default" is misleading as it can't be overwritten anywhere.

Add Varnish exporter to 3rd party section

Update anomaly blog post for new AM and alert syntax

Document without aggregation modifier

small typo on configuration page

Add video from my FOSDEM talk to the media page

Host DreamHack blog post images from repo.