ReSharper: Configure naming convention of private fields
Add cache busting parameter last

As per GA docs
https://developers.google.com/analytics/devguides/collection/protocol/v1
/reference
Add comment on purpose of fragment in URI

This was not clear when reading the code.
HttpClientRequester: Use only POST requests

Instead of GET for URIs below 2000 characters.
POST requests are recommended in the API reference.
https://developers.google.com/analytics/devguides/collection/protocol/v1
/reference
Merge pull request #24 from anjdreas/feature/cleanup

Misc cleanup and commenting