Adjust SDK completely broken with internal server errors when tracking events.

[pateljoel]

I'm currently using this library and after upgrading from 4.2X.X to 4.38.0, I getting lots of HTTP 500 error codes after using the SDK to track events. Similar to the errors found in #215 and adjust/ios_sdk#706. It appears that these issues are still open and unsolved.

In my case the most frequent error I keep seeing in the app is "Device not found" which is not clear to me and there is no documentation around what that means.