The automatic refresh is a safety mechanism in case
file watches fail. As they seem to be working well the
interval can be increased.

Fixes #904

This moves the concern of resolving the files relative to the config
file into the configuration loading itself.
It also fixes #921 which did not load the cert and token files relatively.

Fixes #918, fixes #917

If using A records, the user needs to specify "port" and set "type" to
"A".

This takes the modulus of a hash of some labels.
Combined with a keep relabel action, this allows
for sharding of targets across multiple prometheus
servers.

This commit adds the honor_labels and params arguments to the scrape
config. This allows to specify query parameters used by the scrapers
and handling scraped labels with precedence.

The main purpose of this is to allow for blacklisting
of expensive metrics as a tactical option.
It could also find uses for renaming and removing labels
from federation.

This reverts commit f2f26ca0.

Was accidentally pushed to master instead of a branch for PR.

The main purpose of this is to allow for blacklisting
of expensive metrics as a tactical option.
It could also find uses for renaming and removing labels
from federation.

The YAML parser ignores additional parameters on unmarshaling. This causes
frequent confusion with bad configs that pass parsing.
These changes raise errors on additional parameters.

Fixes issue #787.

This commits adds file based service discovery which reads target
groups from specified files. It detects changes based on file watches
and regular refreshes.

This commit changes the configuration interface from job configs to scrape
configs. This includes allowing multiple ways of target definition at once
and moving DNS SD to its own config message. DNS SD can now contain multiple
DNS names per configured discovery.

- Move CONTRIBUTORS.md to the more common AUTHORS.
- Added the required NOTICE file.
- Changed "Prometheus Team" to "The Prometheus Authors".
- Reverted the erroneous changes to the Apache License.

Essentially:

- Remove unused code.

- Make it 'go vet' clean. The only remaining warnings are in generated code.

- Make it 'golint' clean. The only remaining warnings are in gerenated code.

- Smoothed out same minor things.

Change-Id: I3fe5c1fbead27b0e7a9c247fee2f5a45bc2d42c6

Change-Id: I6bd89e6401bd924315981db797af21bdf0b81252