Release 0.12.0

• removed duplication (8fa0e7e)
• Merge pull request #46 from joernroeder/already-initialized (20c9caf)
• update readme and removed duplicated code (687ed25)
• fixed api keys. thx @larsnystrom (ea1d39e)
• updated tests to fix coverage (95aa781)
• Merge branch 'master' into already-initialized (0f16ef9)
• renamed .release.json to .release-it.json (b64b29b)
• using window._paq to fix tests. #46 (6f3ba53)
• updated external piwik detection to allow instanitation without siteId or url if injectScript is disabled #46 (4d030c3)
• updated Readme (9a87e15)
• added dynamic "already initialized" handling without the need to set a flag manually. heavily inspired by #42. closes #41 (e7b671c)