Promtail updates (#30)

* Make promtail read all its config from a file.

Signed-off-by: Tom Wilkie <tom.wilkie@gmail.com>

* Use gokit logging everywhere.

Signed-off-by: Tom Wilkie <tom.wilkie@gmail.com>

* Start work to parse normal log lines.

Signed-off-by: Tom Wilkie <tom.wilkie@gmail.com>

* update common and kuberesolver.

Signed-off-by: Tom Wilkie <tom.wilkie@gmail.com>

* lint

Signed-off-by: Tom Wilkie <tom.wilkie@gmail.com>

* Get EntryParser stuff working, so we can tail raw log files.

Signed-off-by: Tom Wilkie <tom.wilkie@gmail.com>

* Make sure filename label works.

Signed-off-by: Tom Wilkie <tom.wilkie@gmail.com>

* lint, remove interfacer.

Signed-off-by: Tom Wilkie <tom.wilkie@gmail.com>