* Support multiple masters with retries against each master as required.
* Scrape masters' metrics.
* Add role meta label for node/service/master to make it easier for relabeling.
- Modified sample conf so it is useable by default, also added some
comments from the 'hello world' configuration.
- Updated README so there's a clear two step start for newbies.
- Added extra vim swap files to gitignore.
Change-Id: I76203973db4a7b332014662fcfb2ce5e7d137bd8