Add Tapstream

- Add basic support for [Tapstream](https://tapstream.com/) ([Docs](https://tapstream.com/developer/ios-sdk-documentation/)).
- Add gitignore but its a bit personalised feel free to suggest to modify/remove.
- Bumped version since its a feature addition - but this may mess up how you envisioned next version (again I can change).
- tried to keep to ARAnalytics conventions as much as possible though one thing there isn't precedent for:
  - Providers/TapstreamProvider.m line 49 and 60... throwing exceptions iff DEBUG is true, otherwise do nothing, what do you think?