Explicit link to full install docs added

build: push to Dockerhub and Quay

vendor: update govalidator

Update CircleCI test docker image

Fix git branch with slash as docker tag

Include date and time in graph hover detail.

This is the same solution as applied to PromDash in
https://github.com/prometheus/promdash/pull/72.

Fixes https://github.com/prometheus/prometheus/issues/1569

Fix build for people without $GOPATH/bin in $PATH.

[WIP] New release process using docker, circleci and a centralized building tool

Add discovery capability for Microsoft Azure

building tool

Improve before-relabeling label tooltips.

Yes, the label names and values really need double HTML escaping in
order to end up correctly in the tooltip after two levels of unescaping.

Fixes https://github.com/prometheus/prometheus/issues/1563

Add error message if old alert rule tokens are read

Fix missing printed keep_common without grouping.

Never drop a still open head chunk.

Checkpoint fingerprint mappings only upon shutdown

Before, we checkpointed after every newly detected fingerprint
collision, which is not a problem as long as collisions are
rare. However, with a sufficient number of metrics or particular
nature of the data set, there might be a lot of collisions, all to be
detected upon the first set of scrapes, and then the checkpointing
after each detection will take a quite long time (it's O(n²),
essentially).

Since we are rebuilding the fingerprint mapping during crash recovery,
the previous, very conservative approach didn't even buy us
anything. We only ever read from the checkpoint file after a clean
shutdown, so the only time we need to write the checkpoint file is
during a clean shutdown.

Add link to prometheus.io in the README

Add missing Apache license headers + travis check

Prometheus is Apache 2 licensed, and most source files have the
appropriate copyright license header, but some were missing it without
apparent reason. Correct that by adding it.

Also adds a `check_license` target to the Makefile to run the script

Give TestEvictAndLoadChunkDescs more time to actually evict

Add 0.18.0rc1 changelog