Improve event-handling for analytics

[Waschnick]

• Collect all oil.js events in a queue, so when the tracking tool is not loaded yet the events aren't lost
• Add a description how to create reports for oil.js with Google Analytics
• Detailed documentation

[sschenke]

See https://github.com/as-ideas/oil/pull/148/

[Waschnick]

Merged! What about documentation about how to create reports wie GA?

[Waschnick]

Closed - documentation can be found here https://oil.axelspringer.com/release/1.2.5/docs/index.html#tracking-and-google-analytics-events

I would like to have some Screenshots with example dashboards, but good enough for now.