Add dry run option

[aeirola]

New tracking option to disable dispatching of events. Could possibly also log some debug information. The Android API is a bit strange, would need to figure out what the Package parameter means.

   dryRun: boolean,

See

• https://developers.piwik.pro/en/latest/sdk/Piwik_PRO_SDK_for_Android.html#dry-run
• https://github.com/PiwikPRO/piwik-pro-sdk-framework-ios/blob/1.0.6/PiwikPROSDK.framework/Headers/PiwikTracker.h#L162