Include 2.0b4 changes from official SDK. Change sent Client Version ID.

* Use HTTPS as the default protocol instead of HTTP.
* Track methods changed to Send (e.g. TrackViewAsync now called SendViewAsync)
* Changed Client Version ID to report Android instead of iOS
  - Hoping this will fix device not showing up in Analytics portal
  - Client Version ID format (best guess):
    (m)easurement protocol, (a)ndroid, protocol version (1), client version (b4)
Tagging v2.0.1